which (pron.)

"having the same characteristics or qualities" (as another), c. 1200, lik, shortening of y-lik, from Old English gelic "like, similar," from Proto-Germanic *(ga)leika- "having the same form," literally "with a corresponding body" (source also of Old Saxon gilik, Dutch gelijk, German gleich, Gothic galeiks "equally, like").

This is a compound of *ga- "with, together" + the Germanic root *lik- "body, form; like, same" (source also of Old English lic "body, corpse;" see lich). Etymologically analogous to Latin conform. The modern form (rather than *lich) may be from a northern descendant of the Old English word's Norse cognate, glikr.

Formerly with comparative liker and superlative likest (still in use 17c.). The preposition (c. 1200) and the adverb (c. 1300) both are from the adjective. As a conjunction, first attested early 16c., short for like as, like unto. Colloquial like to "almost, nearly" ("I like to died laughing") is 17c., short for was like to/had like to "come near to, was likely." To feel like "want to, be in the mood for" is 1863, originally American English. Proverbial pattern as in like father, like son is recorded from 1540s.

Meaning "such as" ("A Town Like Alice") attested from 1886. The word has been used as a postponed filler ("going really fast, like") from 1778; as a presumed emphatic ("going, like, really fast") from 1950, originally in counterculture slang and bop talk. Phrase more like it "closer to what is desired" is from 1888.

Old English ælc (n., pron., adj.) "any, all, every, each (one)," short for a-gelic "ever alike," from a "ever" (see aye (adv.)) + gelic "alike" (see like (adj.)). From a common West Germanic expression *aina-galīk (source also of Dutch elk, Old Frisian ellik, Old High German iogilih, German jeglich "each, every"). Originally used as we now use every (which is a compound of each) or all; modern use is by influence of Latin quisque. Modern spelling appeared late 1500s. Also see ilk, such, which.