Caterer

google

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late 16th century: from obsolete cater ‘caterer’, from Old French acateor ‘buyer’, from acater ‘buy’ (see cate).

wiktionary

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From cater +‎ -er.

etymonline

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caterer (n.)

"provider of food or provisions," mid-15c., earlier simply cater (see cater (v.)). With redundant -er (compare poulterer, sorcerer, upholsterer).