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"killer" is also used as a crossword clue. If that's what you saw, the answer is often slayer (6 letters).
Definitions
predatory black-and-white toothed whale with large dorsal fin; common in cold seas
Word origin
From Middle English killer, kyller. By surface analysis, kill + -er.
Used in a sentence
“There’s a killer on the loose.”
“My cat is a habitual bird killer.”
“Carbon monoxide is a silent killer.”
Source: Wiktionary, CC BY-SA 4.0
Used as a crossword answer1 curated clues
01“Murderer”6 letters
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