- -s-s[alternate form of -ES, assimilated to prec. voiceless sounds as (s) and to S voiced sounds as (z) when those sounds are not sibilants] suffix1. forming the plural of most nouns [hips, shoes]2. forming the 3d pers. sing., pres. indic., of certain verbs [shouts, gives, runs]3. forming some adverbs [betimes, days]
English World dictionary. V. Neufeldt. 2014.