Fourth/fɔːrθ/ Definition 1 of 5Pro Tip 1/2Ordinal Numbers Remember 'fourth' is an ordinal number, focusing on position in a sequence, not quantity. His birthday is on the fourth of July. Pro Tip 2/2Spelling Confusion Don't confuse 'fourth' with 'forth'; 'fourth' refers to order, 'forth' means forward. She will present fourth, not forth.