allegiant adjective 1noun 1forms 3 adjective1 •Steadfastly loyal, especially to a monarch or government.In another group, still allegiant to the gangsters, were men such as Shorty, Sorensen, Lars Jacobsen, and Larry. — 1914 noun1 •A person who is loyal to some (specified or implied) thing; one who is allegiant. formsallegiants · more allegiant · most allegiant