Longman Dictionary of Contemporary English - lookout

~ n 1 be on the lookout for to watch a place or situation continuously in order to find something you want or to be ready for problems or opportunities  (Police were on the lookout for anyone behaving suspiciously. | We're always on the lookout for new business opportunities.) 2 keep a lookout to keep watching carefully for something or someone, especially for danger  (keep a sharp/special lookout)  (When you're driving keep a sharp lookout for cyclists.) 3 »PERSON« someone whose duty is to watch carefully for something, especially danger  (A lookout reported an enemy plane approaching.) 4 »PLACE« a place for a lookout to watch from  (a coastguard lookout on the clifftop) 5 it's your/their own lookout BrE spoken used to say that what someone has chosen to do is their own problem or risk, and no one else's  (If he wants to ruin his health with all these drugs, that's his own lookout.) 6 be a poor/bad lookout for sb BrE spoken used to say that something bad or unsatisfactory is likely to happen  (It'll be a poor lookout for James if she finds that letter.)