-s

Inherited from Middle English -s, -es, from Old English -as, nominative-accusative plural ending of masculine a-stem (i.e. strong) declension nouns, from Proto-West Germanic *-ōs, from Proto-Germanic *-ōs, *‑ōz, from Proto-Indo-European *-es, *-oes (plural endings). The spread of this ending in later Middle English was once argued to have been the result of Anglo-Norman influence; however, -as was already the most common Old English plural marker (used in approximately 40% of Old English nouns), and was initially more common in the North of England where French influence was weakest, only later gradually spreading south, replacing the usual southern plural ending -en. Cognate with Scots -s (plural ending), Saterland Frisian -s (plural ending), West Frisian -s (plural ending), Dutch -s (plural ending), Low German -s (plural ending), Danish -er (plural ending), Swedish -r, -ar, -or (plural ending), Icelandic -ar (plural ending), Gothic -𐍉𐍃 (-ōs, nominative plural ending of a-stem masculine nouns). Not directly related to German -er (plural ending) which has a different origin.

From Middle English -(e)s (third-person singular ending), from Northumbrian Old English -es, -as (third-person singular endings). Gradually replaced the older -eth, from Old English -(e)þ, -aþ, during the Middle English and Early Modern English periods. It is predominantly believed that -(e)s is identical to the Old English second-person singular ending -es, -est (cf. archaic Modern English -est, as in thou singest). The use for the third-person singular would have been caused by speakers of Old Norse who switched to speaking English and confounded the endings due to analogy with their native tongue. In Old Norse, the second and third person singular indicative forms were identical (e.g. þú masar, hann masar; þú þekkir, hann þekkir; etc.). An alternative theory sees the shift from /θ/ in -eth to /s/ (later /z/) in -(e)s as a mere phonetic simplification due to the frequency of the ending, but the objection to this is that no such development can be observed anywhere else in English. Nevertheless the relative similarity in sound between both forms may have facilitated the spread of -es.

From Middle English -es, from Old English -es, the masculine and neuter genitive singular ending of strong nouns. More at -'s.

A variant spelling of -'s, partly an archaism, partly by dropping the apostrophe.

Modern sense in slang [circa 1936]. According to OED, a colloquial clipping of the hypocoristic diminutive suffix -sy. As AHD writes, -sy itself usually being informal, ironic and/or jocular, and possibly a combination of -s (“plural marker”) and conflation of -y as adjectival with its sense as a diminutive suffix (e.g., puppy, kitty), the latter notion probably from Scots.

Derived from 's.