Be on the lookout and Be on the look-out

Be on the look-out and be on the lookout are semantically related. In some cases you can use "Be on the look-out" instead a verb phrase "Be on the lookout".

Be on the lookout and be on the look-out are semantically related. Sometimes you can replace phrase "Be on the lookout" with "Be on the look-out", this phrases are similar.