n. (Chem.) A supposed alkaloid obtained from croton oil by boiling it with water and magnesia, since found to be merely a magnesia soap of the oil. Watts. [ 1913 Webster ]
n. 1. singing in a soft low tone; as, her crooning soon put the child to sleep. [ WordNet 1.5 ]
2. the act of singing popular songs in a sentimental manner. [ WordNet 1.5 ]