"in the matter of, in the (legal) case of," c. 1600, probably from Duns Scotus; Latin, from re, ablative of res "property, goods; matter, thing, affair," from Proto-Italic *re-, from PIE *reh-i- "wealth, goods" (source also of Sanskrit rayi- "property, goods," Avestan raii-i- "wealth").

also ingather, 1570s, from in (adv.) + gather (v.). Related: Ingathered; ingathering (1530s).

1913, in electrical wiring, from verbal phrase; see lead (v.1) + in (adv.). General sense of "introduction, opening" is from 1928, originally in music.

also inservice, 1928, from in (prep.) + service (n.).

1892, scientific Latin; "in a test tube, culture dish, etc.;" literally "in glass," from Latin vitrum "glass" (see vitreous).

in reference to of restaurants, banks, etc., built to be patronized without leaving one's car, 1929, from the verbal phrase; see drive (v.) + in (adv.). Of movie theaters by 1933 (the year the first one opened, in Camden, New Jersey).

"persist through adversity," 1969, usually with there; see hang (v.) + in (adv.).

also ingoing, 1825, from in + going. Probably a modern formation unrelated to Middle English in-going (n.) "act of entering" (mid-14c.), from ingo "to go in, enter," from Old English ingan (past tense ineode), equivalent of German eingehen, Dutch ingaan.

1907, from commercial verbal phrase in transit "on the way or passage, while passing from one to another" (1819, earlier in Latin form in transitu), from in + transit (n.).

"a public gathering of hippies" [OED], 1967, from be + in (adv.).