In linguistics, singulative number and collective number (abbreviated SGV and COL) are terms used when the grammatical number for multiple items is the unmarked form of a noun, and the noun is specially marked to indicate a single item. When a language using a collective-singulative system does mark plural number overtly, that form is called the plurative.
Welsh has two systems of grammatical number, singular-plural and collective-singulative. Since the loss of the noun inflection system of earlier Celtic, plurals have become unpredictable and can be formed in several ways: by adding a suffix to the end of the word (most commonly -au), as in tad "father" and tadau "fathers", through vowel mutation, as in bachgen "boy" and bechgyn "boys", or through a combination of the two, as in chwaer "sister" and chwiorydd "sisters". Other nouns take the singulative suffixes -yn (for masculine nouns) or -en (for feminine nouns). Most nouns which inflect according to this system designate objects that are frequently found in groups, for example adar "birds/flock of birds", aderyn "bird"; mefus "a bed of strawberries", mefusen "a strawberry"; plant "children", plentyn "a child"; and coed "forest", coeden "a tree". Still other nouns use suffixes for both singular and plural forms (e.g. merlen "a pony", merlod "ponies", the unsuffixed *merl does not exist); these are similar to nouns formed from other categories of words (e.g. cardod "charity" gives rise to cardotyn "a beggar" and cardotwyr "beggars").
A collective form, such as the Welsh moch "pigs" is more basic than the singular form (mochyn "a pig"). It is generally the collective form which is used as an adjectival modifier, e.g. cig moch ("pig meat", "pork"). The collective form is therefore similar in many respects to an English mass noun such as "rice", which in fact refers to a collection of items which are logically countable. However, English has no productive process of forming singulative nouns (just phrases such as "a grain of rice"). Therefore, English cannot be said to have singulative number.
In Arabic grammar, the singulative is called , "noun of unity". It is formed by the suffixes ? -a(t) and ? -?. The former applies to animals, plants, and inanimate objects, e.g. qam? "wheat", ? qam?a(t) "a grain of wheat"; shajar 'trees', ? shajara(t) 'a tree'; baqar 'cattle'; ? baqara(t) 'a cow'. The latter suffix applies to sentient beings, e.g., jund 'army', ? jund? 'a soldier'; jinn (collective), jinn? (singulative); zinj 'black African people', ? zinj? 'a black African person'.
In East Slavic languages, which are basically of singular-plural system, the singular suffix -- ('-in-', Russian', -yn-', Ukrainian), resp. '-- '('-in-', Belarusian) performs the singulative function for collective nouns. Russian: gorokh (peas in mass) vs. goroshina (a single pea). Ukrainian: /pisok (sand) vs. /pischyna (grain of sand). Belarusian: (potatoes in mass, e.g. as a crop or as a species) vs. (one potato tuber). Notice the affix '-a' in all these examples, which indicates the feminine form. Notice also that plural forms may be derived from these singulatives in a regular way: goroshina->goroshiny (several peas), etc.
In both East Slavic and Arabic, the singulative form always takes on the feminine gender.
In Dutch, singulative forms of collective nouns are occasionally made by diminutives: snoep "sweets, candy" -> snoepje "sweet, piece of candy". These singulatives can be pluralized like most other nouns: snoepjes "several sweets, pieces of candy".