Mainly
来自Big Physics
wiktionary
From Middle English maynly; equivalent to main + -ly.
etymonline
mainly (adv.)
c. 1300, "vigorously, strongly, forcibly" (a sense now obsolete), from main (adj.) + -ly (2). Meaning "especially, chiefly, principally" is from c. 1400; that of "for the most part" is from 1660s.
