The midst is the middle of a group or a situation. Surrounded by it, on all sides.
The word almost never stands alone and lives in two phrases: in the midst of, meaning in the middle of something happening, and in our midst, meaning among us. Both are formal and slightly literary. In the midst of a crisis is the commonest use by far. The word is a shortened form of middest, and amid and amidst are its close relatives, doing much the same job as prepositions.
1nounmidstThe middle of a group, place or situation.
“He arrived in the midst of an argument.”
Midst is middle with an old adverbial s, and then a t added on top. Phrases such as in middes pulled it into that shape, and the extra letter arrived afterwards by analogy.
Old English
midde
Middle English
middes
English, today
midst
Built from
From Middle English middes, midst, myddest (“middle”), from Old English midde, reshaped in Middle English phrases like in middes (“in the middle”) by analogy with adverbs in -s; also compare Old English on middan, tōmiddes. Forms in -(e)st are probably due to influence of superlatives.
Etymology from Wiktionary, CC BY-SA