Single is used with these nouns:
adult, bed, bedroom, bloom, blow, brandy, bulb, bullet, burst, carriageway, category, click, combat, copy, cream, crystal, currency, digit, document, dose, drop, duvet, dwelling, entity, exception, factor, fare, father, figure, focus, friend, garage, girl, individual, instant, item, layer, man, market, mattress, molecule, mother, mum, paragraph, parent, parenthood, payment, people, person, quote, room, row, second, sentence, sheet, shred, soul, source, strand, sweep, syllable, tear, ticket, track, unit, volume, whisky, whole, woman, year