a plural suffix occurring in loanwords from Greek: Hyades.
var. of -s 2 in verbs ending in s, z, ch, sh, or post-consonantal y: passes; buzzes; pitches; dashes; studies.
var. of -s 3 in nouns ending in s, z, ch, sh, or post-consonantal y, and in nouns in f with v in the plural: losses; fuzzes; riches; ashes; babies; sheaves.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.