(Australia, UK, New Zealand) A length of sawn wood of cross section 4 inches by 2 inches, most often employed as structural framing lumber / timber.

(baseball, slang) A home run.

(In both the 12-hour clock and the 24-hour clock) The start of the fifth hour of the day; 4:00 a.m. (04:00). / (Only in the 12-hour clock) The start of the seventeenth hour of the day; 4:00 p.m. (16:00).

Acknowledgment of message received.

(Canada, slang) A case of twenty-four bottles or cans of beer.

A law student in his or her fourth year of law school; generally an unusual situation occurring where a student has either taken an extended part-time curriculum, or has failed a class needed for graduation and must stay on for an extra semester after the three L year.

The cardinal number occurring after three hundred ninety-nine and before four hundred one, represented in Arabic numerals as 400.

(slang, Canada, US) A lowly, disreputable cheat or fraudster, especially at cards, especially a dull or unimaginative one.

A horse-drawn hackney cab with four wheels, as opposed to a hansom or dogcart. / Any vehicle with four wheels.

A method of encoding Chinese characters using four numerical digits per character (in some situations, an additional digit is used).