A person who apologizes or who makes apologies (British spelling).
From apologise (British form of apologize) + -er agent suffix. Developed from Greek apologos 'answering' through Old French and Latin, with the -ise/-ize verb form creating agent nouns via -er.
The split between British 'apologiser' and American 'apologizer' reflects the Great Vowel Shift and different standardization paths in English—the -s- vs -z- difference shows how the same language evolved differently across the Atlantic.
Complete word intelligence in one call. Free tier — 50 lookups/day.