Meaning A girl's name of English origin, it means "Variant of Thomasina 'Twin'." Origin of Tamsin English Popular Middle Names Pronunciation 🔊 Listen Tamsin TahMSIHN Similar Names Tammie Tamassa Babirye Tassie Tamzin Tomasina Thomasin Thomsina Tomasine Thomasa Year by Year Popularity of Tamsin