LATIN DICTIONARYLexicon Latīnum
prefix

sēm-

sēm-
Classical[ˈseː.m]Ecclesiastical[ˈsɛː.m]

Meaning

  1. morphemePrevocalic form of sēmi-
    semnoctua vel nocticoraxhalf-owl or night-crow (nightjar)

Quick answers

What does sēm- mean in Latin?
sēm-, a prefix, means “Prevocalic form of sēmi-”.
How do you pronounce sēm-?
In classical Latin, [ˈseː.m]; in ecclesiastical (church) Latin, [ˈsɛː.m].