[ sem-ee-fawr-muh l, sem-ahy- ]
/ ˌsɛm iˈfɔr məl, ˌsɛm aɪ- /
partly formal; containing some formal elements: a semiformal occasion; semiformal attire.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for semiformal
What additional formal or at least let us say semiformal instruction or education have you had in the Russian language?Warren Commission (3 of 26): Hearings Vol. III (of 15)|The President's Commission on the Assassination of President Kennedy
The most enjoyable dinner is that with four or six guests, which is served in a simple and only semiformal way.The Etiquette of To-day|Edith B. Ordway