Most Indo-European n-stem nouns are either individualizing, e.g. Avestan marətan- ‘mortal’, i.e. ‘the dead one’, or they denote body parts, e.g. Greek ōlḗn ‘elbow’. In this article, it is argued that most Indo-European n-stems denoting body parts originally had a singulative function, denoting a single instance of a body part of which the body has more than one. This analysis allows us to connect the ‘body part’ function of the Indo-European suffix *-n- to its well-established individualizing function. The following evidence in favour of a singulative suffix *-n- will be discussed: (1) the productive singulative suffix *-(e)n-i̯o- in Celtic; (2) suppletive paradigms in various Indo-European languages in which a singular is (based on) an n-stem, e.g. Armenian duṙn, pl. durk‘ ‘door, gate’, Gothic kaurno ‘single grain’, kaurn ‘corn’, Russian súdno, pl. sudá ‘vessel’; and 3) words for body parts naturally occurring in pairs or larger quantities which are attested with and without the nasal suffix, e.g. Armenian akn, Gothic augo and Old Prussian agins ‘eye’, but without a nasal Greek ósse and Old Church Slavic oči ‘eyes’.