amongst (prep., adv.)

"in, in the midst of," early 12c., from Old English onmang, in late Old English sometimes amang, a contraction of ongemang "among, during," from the phrase on gemang, literally "in the crowd or company (of)," from on (see a- (1)) + gemengan "to mingle." Ths second element is from Proto-Germanic *mangjan "to knead together," which is perhaps from a nasalized form of PIE root *mag- "to knead, fashion, fit."

The collective prefix ge- was dropped 12c. leaving onmong, amang, among. Compare Old Saxon angimang "among, amid;" Old Frisian mong "among."

a variant of amid (q.v.) with adverbial genitive -s and unetymological -t. Amidde became amyddes (13c.) and acquired the -t from mid-15c., probably by association with superlatives in -st; the pattern also yielded amongst, against, betwixt, whilst, also archaic alongst (13c.-17c.).

There is a tendency to use amidst more distributively than amid, e.g. of things scattered about, or a thing moving, in the midst of others. [OED]

"bidding, command," Old English hæs "bidding, behest, command," from Proto-Germanic *hait-ti-, from *haitan "to call, name" (see behest). With unetymological -t added in Middle English on model of other pairings (compare wist/wesan, also whilst, amongst, etc.; see amidst).