The verb explain has 3 senses (first 3 from tagged texts)
1. (114) explain, explicate -- (make plain and comprehensible; "He explained the laws of physics to his students")
2. (12) explain -- (define; "The committee explained their plan for fund-raising to the Dean")
3. (7) excuse, explain -- (serve as a reason or cause or justification of; "Your need to sleep late does not excuse your late arrival at work"; "Her recent divorce may explain her reluctance to date again")