WordNet (r) 3.0 (2006):

look out
    v 1: be vigilant, be on the lookout or be careful; "Watch out
         for pickpockets!" [syn: watch, look out, watch out]
    2: to protect someone's interests; "A man's gotta look out for
       his family"

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "look out":
   and listen, attend to business, be alert, be obsessed with,
   be vigilant, be watchful, beware, concentrate on, fix on, focus on,
   give heed, have a care, keep alert, keep in sight, keep in view,
   keep vigil, keep watch, lie low, look, look about one, look lively,
   look sharp, mind, miss nothing, never nod, pay attention, pay heed,
   qui vive, scrutinize, stop, study, take care, take heed, watch,
   watch out