something n., pron.

Middle English som, "someone, somebody, a certain person; a certain indefinite portion of something, some part," from Old English sum "some, a, a certain one, something, a certain quantity; a certain indefinite number" (as in some say). This is from Proto-Germanic *sumaz (source also of Old Saxon, Old Frisian, Old High German sum, Old Norse sumr, Gothic sums), from a suffixed form of PIE root *sem- (1) "one; as one, together with."

The word has had greater currency in English than in the other Teutonic languages, in some of which it is now restricted to dialect use, or represented only by derivatives or compounds .... [OED]

For substitution of -o- for -u-, see come. As a pronoun from c. 1100, "a certain quantity or number." A possessive form is attested from 1560s but remains rare. Use as a quasi-adverb before numerals began in Old English, originally "out of" (as in sum feowra "one of four").

The sense of "in some degree, to some extent" is American English, by 1745. The meaning "remarkable, quite a" is attested from 1808, American English colloquial.

Many combination forms (somewhat, sometime, somewhere) were in Middle English but often written as two words before 17-19c. Somewhen is rare and since 19c. used almost exclusively in combination with the more common compounds; somewho "someone" is attested from late 14c. but did not endure. Somewhy appeared occasionally in 19c. Scott (1816) has somegate "somewhere, in some way, somehow," and somekins or somskinnes "some kind of a" is recorded from c. 1200.

Get some "have sexual intercourse" is attested 1899 in an anecdote of Abe Lincoln from c. 1840.

Old English þing "meeting, assembly, council, discussion," later "entity, being, matter" (subject of deliberation in an assembly), also "act, deed, event, material object, body, being, creature," from Proto-Germanic *thinga- "assembly" (source also of Old Frisian thing "assembly, council, suit, matter, thing," Middle Dutch dinc "court-day, suit, plea, concern, affair, thing," Dutch ding "thing," Old High German ding "public assembly for judgment and business, lawsuit," German Ding "affair, matter, thing," Old Norse þing "public assembly"). The Germanic word is perhaps literally "appointed time," from a PIE *tenk- (1), from root *ten- "stretch," perhaps on notion of "stretch of time for a meeting or assembly."

The sense "meeting, assembly" did not survive Old English. For sense evolution, compare French chose, Spanish cosa "thing," from Latin causa "judicial process, lawsuit, case;" Latin res "affair, thing," also "case at law, cause." Old sense is preserved in second element of hustings and in Icelandic Althing, the nation's general assembly.

Of persons, often pityingly, from late 13c. Used colloquially since c. 1600 to indicate things the speaker can't name at the moment, often with various meaningless suffixes (see thingamajig).

Things "personal possessions" is from c. 1300. The thing "what's stylish or fashionable" is recorded from 1762. Phrase do your thing "follow your particular predilection," though associated with hippie-speak of 1960s is attested from 1841.