particular (n.) Look up particular at Dictionary.com
"a part or section of a whole," late 14c., from particular (adj.). Particulars "small details of statement" is from c. 1600.
particular (adj.) Look up particular at Dictionary.com
late 14c., "pertaining to a single thing or person," from Old French particuler (14c., Modern French particulier) and directly from Late Latin particularis "of a part, concerning a small part," from Latin particula "little bit or part, grain, jot," diminutive of pars (genitive partis) "a part, piece, division" (from PIE root *pere- (2) "to grant, allot"). Sense of "precise, exacting" first recorded 1814.