What does the name Alison mean?

According to "A Dictionary of First Names" by Hanks and Hodges, Alison is a diminutive form of the French name, "Alice." In turn, "Alice" is an English and French variant of "Adelaide", an Old French spelling of a greatly contracted Germanic name, "Adalheidis" That name consists of two elements: "adal," meaning "noble", and "heid," meaning "kind." (This is probably "kind" in the sense of "type" rather than as someone who takes care to think about other's feelings.) Alison means "noble" in French.