Baseball official, familiarly

UMP

This person often yells "Strike!" or "Out!" and wears a black uniform behind home plate during games.

Baseball official, familiarly" is a straightforward clue asking for the informal term for an umpire. The word "familiarly" signals that the answer is a shortened or casual version of the full word, which is why "ump" fits instead of "umpire." It’s a common nickname used in sports commentary and everyday conversation about baseball.