Kalev (כלב) is a compound of the two words kal/kol (כל), “whole or all”, and lev (לב) “heart”, simply meaning “wholehearted”, because he pursued after YHVH with all his heart and was rewarded for his obedience toward Him, as recorded in the Torah. It is often confused for the word kelev (כלב), which means “dog”, sharing the same 3 letters but having differing vowel points.