Learn English – the term used for people who drive slowly

Purely in terms of the terminology, then a distinction sometimes made is that:

• inflectional subjunctive is the type found in Old English, German, modern Romance languages etc, in which verbal inflection distinguishes subjunctive from indicative;
• periphrastic subjunctive is the type found (if you adopt this analysis) in modern English, in which subjunctive is distinguished from indicative by way of modal auxiliaries/other verbal constructions.

There's really no consensually agreed upon "wrong" or "right" answer to the question of whether English actually "has a subjunctive". If you adopt the analysis that "subjunctive" is the grammaticalisation of non-assertive force with a verbal paradigm-- which seems to be a close approximation to what the phenomenon is in Romance languages-- then it's fairly clear that English doesn't have such a phenomenon. (Saying that English has a past subjunctive on the basis of the form "if it were" is a bit like saying that English is a verb-final language on the basis of a phrase such as "Language does not a society make": it's proposing a paradigm on the basis of a rare exception.)

If you extend the definition to cover cases such as English "It is sad that he should leave", "David commanded that she leave" etc, then there are various issues to be considered which are typically glossed over in language learning textbooks:

• care must be taken to recognise where the similarities and differences actually lie between these phenomena and the inflectional subjunctives of French etc;
• it is worth thinking about what the motivation is for proposing "subjunctive" as a 'special case' of modal verb usage.

According to http://www.merriam-webster.com/dictionary/pool, the word "pool" meaning a body of water and the word "pool" meaning an aggregation are different words with different etymologies. Wiktionary agrees: http://en.wiktionary.org/wiki/pool#Etymology_1 and http://en.wiktionary.org/wiki/pool#Etymology_2.

The second etymology explains that the word comes from:

French poule ("collective stakes in a game") (The OED suggests that this may be a transferred use of poule (“hen”), which has been explained anecdotally as deriving from an old informal betting game in France - 'jeu de poule' - Game of Chicken (or Hen, literally) in which poule became synonymous with the combined money pot claimed by the winner)

I suspect that the gambling analogy came about because of the random manner in which genes are passed from parent to offspring in sexual reproduction. Collectively, a species has some repertoire of genes to which all parents contribute, and from which all offspring take.