Q: I’m confused about the verb “baby-sit.” Common usage today seems to be this: “I baby-sit my little brother.” My belief is that it should be “I baby-sit with my little brother.” Also, would one baby-sit with a neighbor? Or with a plant? Can you clear this up for me?
A: The verb “baby-sit” (sometimes “babysit”) has an interesting history. It was apparently formed from the noun “babysitter.” The noun came first (in the 1930s), followed by the verb (in the 1940s). Linguists call this a back-formation.
As a verb, “baby-sit” can be either transitive (“She baby-sits my little brother”) or intransitive (“She baby-sits for [or “with”] my little brother.”) And, yes, one can baby-sit with a neighbor or a plant.
All this comes from the American Heritage Dictionary of the English Language, which has an interesting word history for baby-sit.”