look out for

1. See to the welfare of, as in Mary was assigned to look out for the youngsters on the playground . Similar to look after , this expression appears in such terms as look out for number one , meaning “see to one's own best interests,” as in Looking out for number one is Barbara's first priority . Versions of this expression, such as take care of number one , date from 1700.

2. Be careful of or watchful for something or someone, as in Look out for broken glass on the floor , or Look out for Mary—she'll be coming any minute . [Second half of 1600s] Also see look out .