1. 了望人员：lookout house 了望屋 | lookout man 了望人员 | lookout observatory 了望观察台

2. 了望员：lookout man 瞭望员 | lookout man 了望员 | lookout on the forecastle 瞭头

3. 瞭望员：lookout bridge 了望桥楼 | lookout man 瞭望员 | lookout man 了望员

noun

1. a person employed to keep watch for some anticipated event

Synonym: lookoutsentinelsentrywatchspotterscoutpicket