four; four years of age; ten o'clock (old time system); Burakumin; cross grips
fourth day of the month; four days
crawling on all fours; getting on one's hands and knees; falling flat
fourteenth day of the month; fourteen days
twenty-fourth day of the month; twenty-four days
fundamental interactions; four fundamental forces of nature
the Four Freedoms (as defined by Franklin D. Roosevelt: freedom of speech, freedom of worship, freedom from want, freedom from fear)