four; four years of age; ten o'clock (old time system); Burakumin; cross grips
four-character compound word (esp. idiomatic)
the four cardinal directions; north, east, south and west; all directions; four sides (of a square)
24 hours; twenty-four hours
four and a half tatami mats; four-and-a-half-mat room; small room esp. for assignations
four corners; four ordinal directions
fourth dimension; four dimensions
crossroads; intersection; crossway; carrefour
four-digit number; thousands column
Yom Kippur War; fourth Arab-Israeli war (October 6-25, 1973)
yodan verb conjugation; verb conjugation of classical Japanese
four-letter word (vulgar English term, e.g. fuck)
Chinese four-character phrase or idiomatic expression