While Americans (and possibly others) pronounce this as "loo-tenant", folks from the UK pronounce it as "lef-tenant".
Why?
british-englishpronunciationpronunciation-vs-spelling
While Americans (and possibly others) pronounce this as "loo-tenant", folks from the UK pronounce it as "lef-tenant".
Why?
Short answer: English spelling does not display a one-to-one correspondence with pronunciation, and certainly not with modern pronunciation. You shouldn't expect it to.
Medium answer: These words are spelled with the same letter combination but pronounced with different sounds due to a combination of different etymologies, and different sound changes. Some of them started out with different pronunciations and stayed different; some of them started out with the same pronunciations and diverged over time.
Long answer: Some words have spellings in modern English that never corresponded to their pronunciations and were only established by analogy with other words with a similar meaning. This seems to be the case for the following two words spelled with "ough":
hiccough: the word is not actually derived from cough. But people started spelling it with -ough because they thought it seemed similar to cough. The more regular spelling with "up" is still commonly used.
furlough, which comes from Dutch verlof; I have no idea why it changed pronunciation and spelling.
There are many other words that exhibit this phenomenon: island (never pronounced with an s), scissors (with extraneous s; it comes from the root cis- as in incision but was mistakenly thought to come from the root sciss- as in scission), foreign (never pronounced with g; it was apparently respelled by analogy with words like sovereign), ptarmigan (never pronounced with p).
However, most words spelled with gh did originally have a corresponding consonant sound in this position: a velar fricative /x/ (which can still be seen in related words in some other Germanic languages, as Roger Mue's answer shows). The spelling gh was one of the usual ways of representing this sound in Middle English. The words are pronounced differently now because they underwent sound changes. In all languages, words change in pronunciation over time. In some words, the sound /x/ changed to /f/ (see this question to learn why: Why did /x/ change to /f/ in English?), while in others it was dropped, but caused the previous vowel to become a diphthong. The sound change turning /x/ to /f/ only applied sporadically, so the sounds in some words shifted one way while in others they shifted a different way. The vowels also changed in various ways, sometimes irregularly.
To try to see if there were any regular patterns, I divided the words into several "classes" based on how they are pronounced.
I'll use the abbreviation "OE" to stand for "Old English" and "ME" to stand for Middle English. Be aware that the historical forms I list are not comprehensive. The forms are taken from the Oxford English Dictionary (OED), New Oxford American Dictionary, and Wiktionary. The words on the left have an arrow < pointing to them to show that they descend from the words on the right. Words preceded by an asterisk are hypothetical/reconstructed rather than attested forms.
ough = /ɔː/ "aw" sound as in jaw:
ough = /aʊ/ "ow" sound as in cow:
sough (v/n) < OE swōgan (v), ME *swōh, swōȝ (n) (—also has /ʌf/, maybe had /ɒf/)
The words listed above all had long "ō" in Old English. Normally, this developed to an "oo" sound (as in goose), but it seems to have followed a different path in these words. It seems that it joined with long "ū" in Middle English, and then developed to the diphthong that is currently present (Eilert Ekwall, ed. 1907, Dr John Jones's Practical Phonography (1701)). (One possible exception is slough, which is often pronounced as sloo/slew.)
I think we could compare this to the development of some Old English /e/ or /ea/ followed by /g/ or /x/ to late Middle English long "ī," as in the words "eye" < OE ēage and "die." (And interestingly, this change also seems to have been sporadic: compare the pronunciations of "eight" and "height.")
Another possibly significant fact is that all of the above words had variants with g instead of h in inflected forms, such as the plurals; and in fact the now-archaic enow was used as the plural form of enough. I found that several authors say for this reason that these forms actually derive from Old English forms with g rather than with [x] (Wyld 1907). Old English single /g/ was vocalized between vowels, so if the etymology from these forms is accurate, the overall development would have been something like [oːg] (Old English) > [oːw] > [uː] > [aʊ]. This is distinct however from what seems to be the usual development of Old English [oːw] (as in "flōwan" > modern "flow," with [oʊ] not [aʊ]).
drought; discussed in the explanation of the "ought" words above, in 1.
ough = /oʊ/ "oe" sound as in toe:
borough < ME burwe among other forms < OE burg/burh
The significant fact here is that "ough" is in an unstressed syllable in both of these words where it is pronounced as /oʊ/. I would guess these developed similarly to words like furrow (from ME forwe among other forms < OE furh), arrow (from OE earh/arwe), and sparrow (from OE spearwa). That is, the final h or g was replaced with the semivowel w, which subsequently developed into an oaw sound. For some speakers, the current pronunciation has developed further to a schwa sound /ə/.
dough < OE dāh
This word had long "ā" in Old English. Normally, this developed to an "o/oa/oe" sound in Modern English (as in cold, stone or toe) and this seems to have occurred here as well, as least for the standard pronunciation. One dialectal pronunciation is discussed further down.
though < Old Norse *þōh
This is another word that shows several phonetic variants in different dialects, which perhaps is to be expected as it seems to have a complicated etymology. The Oxford English Dictionary gives the following explanation:
Old Norse *þóh (intermediate to þauh and þó), [was] shortened in Ormin to þŏhh, with subseq. stress-lengthening to þōuȝ, though, thō. The Norse form gradually gained over [the Old English forms], which disappeared from literature before 1500. [Other] forms show the same development of f < ȝ, gh /x/, as in laugh, cough, tough; thof was occasional in literature as late as 1750, and is still prevalent in many varieties from Yorkshire and Lancashire to Hampshire and Devon: see Wright Eng. Dial. Gram. In Scotl. and north of Engl. though is pronounced /θɔː/; the Hampshire and West Somerset thof also is /θɔf/, not /ðɔf/.
ough = /ɒf/ "off" sound:
trough < OE trog/troh
These two words have the normal “short o” vowel. This makes sense because they both had a short "o" in old English, although it was pronounced differently from how it is now (it was literally a shorter version of the long ō sound). However, there are not enough ough words with this pronunciation in Modern English to say if the development was "regular" or not. They also show the change of [x] > /f/.
sough (n) < OE swōgan (v), ME *swōh, swōȝ (n) (obsolete variant pronunciation): the OED entry for the noun sough says "The pronunciation /sɒf/ is given by Smart (1836) and Ogilvie (1850)." But it is usually pronounced with /aʊ/ or /ʌf/. This word is ultimately from Old English swōgan, with a long vowel, so the development to /sɒf/ could indicate the activity of some kind of shortening sound change in this context. However, the pronunciation might have been altered by analogy rather than by a sound change.
ough = /ʌf/ "uff" sound:
ough = /uː/ "oo" sound:
There is also some variation between these pronunciations for several words.
Bibliography:
I'd say that your German colleagues are mishearing the English pronunciations.
The German letter ü makes the sound [y], which does not occur in English.
The words loose, poodle, food, and most other words with oo have the vowel [u], which is usually spelled u or uh in German. Historically this is a long /o/ sound that was written with "oo", the pronunciation of which has shifted to [u] as a result of the Great Vowel Shift.
Some words with oo have instead the vowel [ʊ]: good, hood, book. There is no rule that predicts which words have this pronunciation, so you have to memorize it. The [ʊ] sound occurs in German as an allophone of /u/ in closed syllables. The vowel [ʊ] is shorter, more lax, and slightly centralized relative to [u]. This sound also tends to come from an older long /o/, though the reasons for this split are complicated and obscure.
A very small number of words with oo are pronounced with an [o] vowel: door, floor. These words always end in r, because the final r colors the preceding vowel. This is the same sound that is spelled o or oh in German.
Best Answer
Etymonline indicates that spelling with lef- dates to the 14th century, but that the origins of that spelling (and presumably its associated pronunciation) are “mysterious”. The word comes originally from Old French, and according to the OED, Old French replaced word- and syllable-final [w] with [f]; for the Modern French word lieu, this is shown by an Old French spelling variant luef. Both forms, whyever they exist, just happened to stick.