Albert Barnes Commentary 1 Kings 14:5

"And Jehovah said unto Ahijah, Behold, the wife of Jeroboam cometh to inquire of thee concerning her son; for he is sick: thus and thus shalt thou say unto her; for it will be, when she cometh in, that she will feign herself to be another woman." — 1 Kings 14:5 (ASV)

Feign herself to be another woman - This literally means, “she shall make herself strange,” that is, “she shall come in disguised.” See 1 Kings 14:6.