Something that faces or confronts you directly; a problem or challenge that must be dealt with head-on; or one who faces something.
From 'face' plus '-er' (agent suffix). British slang from 19th century, originally meaning a remark or blow delivered directly to the face.
A 'facer' in British slang was literally a punch to the face, then became any stunning piece of unexpected bad news—like getting hit by reality—which shows how physical experience becomes metaphor in language!
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