hermatile Share definition Flag Acting disproportionately crazy to a situation; running amok and generally reacting badly Percival went hermatile when his tuna sandwich came up missing from the snack room refrigerator and had to be sedated and take a paid day off. hermatile by harry flashman July 7, 2003 0 0 Get merch Get the hermatile mug. Buy Now — $32.95 See more merch