howler comes from howl (of imitative origin, from Middle English houlen) + -er; the 'glaring mistake' sense developed colloquially in the 19th century. Morphologically, the ending is part of the etymology: the suffix is attached to the older base named in the history, producing a later English derivative. The etymology remains cautious where the history is cautious: comparisons, echoic formation, or disputed derivation do not make the ancestry more definite than the forms actually named. In present English, the noun sense is "a glaring and ludicrous mistake; also an animal that howls", so the historical development ends in a clearly identifiable modern dictionary use. The same base also appears in related forms such as howl. Its semantic neighborhood includes blunder, gaffe, mistake, and error, which helps locate the modern sense without adding a separate etymological claim. The named historical forms include Middle English houlen and onomatopoeic howl.