Definition of "semi-formal" [semi-formal]

• Moderately formal; requiring a dinner jacket (adjective)

WordNet. Princeton University. 2010.

• "The hall was filled with a youthful exuberance, which speaks of many unsold seats and a plethora of rush tickets distributed to individuals excited to find another use for their semi-formal garb and all too eager to splash on cologne."
• "As Vance put it: not bad but wrong or at least ill-advised in formal or semi-formal prose — which may be what you meant by “bad”."
• "Taking stacks of newspaper, glue and water, I skipped my high school semi-formal dance to give my girl some skin."