Learn English – What English word can be used to describe someone indirectly helping you

The origin of the word 'tut' as a noun is, as of yet, unknown. The OED entry for Tut says:

Etymology: There is perhaps more than one word here. Of the origin nothing has been ascertained.

However, the use of the word 'tut' in the 'rubbish' sense may be supported by this definition from the OED:

a. Orig. in the Cornish tin-mines, now also in Derbyshire lead-mining: in the phrase upon tut (also by the tut), and attrib. as tut-bargain, tut-man, tut-work (also as vb.), tut-worker, tut-working, tut-workman: denoting a system of payment by measurement or by the piece, adopted in paying for work which brings no immediate returns, as distinct from tribute n. 3; hence, work of this character; dead-work.

The OED takes less of a cop-out on Tut, v. saying:

Etymology: A natural utterance; the spelling tut sometimes represents the palatal click (also spelt tchick n., tck int.).

Which may also explain the etymology of the slang word - being something that is just replaced for a word that is better left unsaid - a sort of self-censorship of more appropriate or cruder language.

Ultimately my guess would be that it's some combination of the two.

A given individual's idiosyncratic use of language or words is called an idiolect, and a single word with multiple or ambiguous meanings can be described as multivalent but for generally describing the varying meanings of words, semantics is in fact correct. When you say "we are arguing semantics" you mean "we are arguing over the meanings/definitions of our words."

It's a little off topic for this SE, but it's worth mentioning that a number of noted philosophers have devoted their careers to semantics and the impact of semantics on philosophical debates.