English spelling can be a difficult concept to grasp. There are some words which are spelled differently depending on where they’re used, and some that are spelled in ways that don’t correlate at all with how they’re pronounced when spoken aloud. Fortunately, some spelling differences are easy to remember. The words forth and fourth only have one letter’s difference between them, but they are actually completely different parts of speech. Additionally, there is a very simple way to remember which word belongs in which context.
Forth as adverb:
We rose at dawn and sallied forth.
Forth also means onwards in time.
Fourth as number:
Sales of existing Canadian homes fell 3.1 percent in August from July, the fourth straight monthly decline and the largest drop in nearly two years, a report from the Canadian Real Estate Association showed on Thursday. (Reuters)
Kaori Icho won a historic fourth straight gold medal and Japan claimed a clean sweep on the wrestling mat as Eri Tosaka and Sara Dosho also topped the podium at the Rio Olympics on Wednesday. (The Japan Times)
Fourth or forth:
These two words, while spelled similarly, have completely different meanings and functions in the sentence. Forth is an adverb that means forward or ahead. Fourth is an adjective that means an item in a sequence preceded by three earlier items. The two words are never interchangeable; they are different parts of speech. You can remember that fourth represents a number in a sequence since its spelling includes the word four.