late 14c., "deduction or inference reached by reasoning, result of a discussion or examination," from Old French conclusion "conclusion, result, outcome," from Latin conclusionem (nominative conclusio), noun of action from past-participle stem of concludere "to shut up, enclose" (see conclude).
Also, from late 14c. "the end, termination, final part; closing passages of a speech or writing; final result, outcome." For foregone conclusion, see forego.
(klōz), late 14c., "act of closing, conclusion, termination," from close (v.). Also in early use "enclosure, enclosed space" (late 13c.), from Old French clos, noun use of the past participle. Specifically in music, "conclusion of a strain or passage," 1590s.