not appropriate in application; defective; "an infelicitous remark"; "infelicitous phrasing"; "the infelicitous typesetting was due to illegible copy"
marked by or producing unhappiness; "infelicitous circumstances"; "unhappy caravans, straggling afoot through swamps and canebrakes"- American Guide Series
having momentous consequences; of decisive importance; "that fateful meeting of the U.N. when...it declared war on North Korea"- Saturday Rev; "the fatal day of the election finally arrived"