c.1300, "attendance at court, the company attending," also their livery or uniform, via Anglo-Fr. siwte, from O.Fr. suitte "attendance, act of following," from Gallo-Romance *sequita, fem. of *sequitus, from L. secutus, pp. of sequi "to attend, follow" (see sequel
"application to a court for justice, lawsuit" is first recorded early 15c. Meaning "set of clothes to be worn together" is attested from early 15c., from notion of the livery or uniform of court attendants (a sense recorded from late 13c.). As a derisive term for "businessman," it dates from 1979. Meaning "set of playing cards bearing the same symbol" is first attested 1520s, also from the notion of livery. Hence, to follow suit (1670s), which is from card playing. Suitcase first recorded 1902, originally a case for holding a suit of clothes.
"be agreeable or convenient," 1570s, from suit
(n.), probably from the notion of "provide with a set of new clothes." Suitor "man who is courting a woman" is 1580s, from earlier notion of "adherent, follower" (late 14c.).