IPA: //ˈteɪbəlˌmeɪt//
KK: /ˈteɪbəlˌmeɪt/
A person who sits at the same table as someone else, especially during a meal.
She enjoyed chatting with her tablemate during dinner.
Tablemate is formed from "table" (from Old French *table*, meaning a flat surface for working or eating) and "mate" (from Old English *gemetta*, meaning a companion or associate). The word "tablemate" refers to a companion or associate who shares a table with someone, typically during a meal or gathering.
Think of someone who shares a 'table' with you — that's your 'tablemate', a companion at the table.