late 12c., mycrocossmos (modern form from early 15c.), "human nature, man viewed as the epitome of creation," literally "miniature world," from Medieval Latin microcosmus, from Greek mikros "small" (see micro-) + kosmos "world" (see cosmos).
General sense of "a community constituting a world unto itself, a little society" is attested from 1560s, perhaps from French microcosme. A native expression in the same sense was petty world (c. 1600).
Forrþi mahht tu nemmnenn mann Affterr Grikkishe spæche Mycrocossmos, þat nemmnedd iss Affterr Ennglisshe spæche Þe little werelld. ["Ormulum," c. 1175]
Middle English -ik, -ick, word-forming element making adjectives, "having to do with, having the nature of, being, made of, caused by, similar to," from French -ique and directly from Latin -icus or from cognate Greek -ikos "in the manner of; pertaining to." From PIE adjective suffix *-(i)ko, which also yielded Slavic -isku, adjectival suffix indicating origin, the source of the -sky (Russian -skii) in many surnames. In chemistry, indicating a higher valence than names in -ous (first in benzoic, 1791).
In Middle English and after often spelled -ick, -ike, -ique. Variant forms in -ick (critick, ethick) were common in early Modern English and survived in English dictionaries into early 19c. This spelling was supported by Johnson but opposed by Webster, who prevailed.
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Harper, D. (n.d.). Etymology of microcosmic. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/microcosmic