The term LIKE ONE HATTER can be solved by the crossword solution MAD, which is an acronym for 'mentally ill or disturbed'. This phrase is often used to describe someone who is suffering from a mental disorder or illness. It is also used to refer to someone who behaves in an irrational or unpredictable manner. The phrase is derived from the character of the MAD Hatter in Lewis Carroll's Alice's Adventures in Wonderland.