The suffix -ster/stər/ is a nominalizing Germanic suffix of unclear origin (see Etymologiebank) that can be used productively to create nouns of common gender referring to female persons. It is the counterpart of nominalizations with the suffix -er (which may be seen as an instance of affix substitution) or it uses as its basis nominalizations in -aar and -ier.

• -ster functions as the counterpart of deverbal -er formations, which can be seen as a case of paradigmatic word formation or affix substitution, because (unlike affix sequences such as -ier-ster and -aar-ster, cf. below) the affix sequence -er-ster does not occur. Verbal bases can be both simplex (e.g. kapsterfemale hairdresser corresponding to kapperhairdresser < kappento cut, to chop) or complex (ontvangsterfemale receiver next to ontvangerreceiver, tax-collector < ont-vangento receive). If for whatever reason an -er derivation is impossible, then so is a derivation with -ster: no *valler or *valster on the basis of ergative vallento fall, no *schamer or *schaamster from obligatory reflexive zich schamento be ashamed, no *blijker or *blijkster from subjectless blijkento turn out. If the stem of the formation in -er has a special form, then so has the one in -ster, e.g. reizigster with extra -ig- next to reizigertraveller (< reizento travel), tegenstandster with stem allomorphy next to tegenstanderopponent (< tegenstaanagainst-standto oppose).

  -ster formations as counterparts of non-deverbal -er derivations are rare: no *rechtster as female counterpart to rechterjudge, no *tienster next to tienerteenager, no *Amsterdamster next to Amsterdammersomeone from Amsterdam. De Haas and Trommelen (1993:191) do, however, list examples such as dagloonsterfemale day laborer (cf. daglonerday laborer < dagloonday's pay), wetenschapsterfemale scientist (cf. wetenschapperscientist < wetenschapknowledge-shipscience), misdadigsterfemale criminal (cf. misdadigercriminal < misdaadwrong-deedcrime), vrijwilligsterfemale volunteer (cf. vrijwilligervolunteer < vrijwilligfree-will-SUFFvoluntarily) and VVD'sterfemale member or supporter of the political party VVD (cf. VVD'ermember or supporter of the political party VVD), which may all be analyzed as cases of affix substitution.

• Regular deverbal -aar formations get, in principle, a female counterpart in -ster: wandelaar-sterfemale walker, verzamelaarsterfemale collector. The same holds for certain other -aar derivations: beoordelaarsterfemale evaluator (< beoordelento evaluate), leugenaarsterfemale lier (< leugen.Nlie). -ster also attaches to person names with suffix -ier, e.g. winkeliersterwinkel-ier-sterfemale shop keeper and avonturiersteravontuur-ier-sterfemale adventurer.

The suffix -ster does not bear stress and does not change the stress pattern of its base. Due to the phonological make-up of the affix, there will always be a syllable boundary coinciding with the morphological boundary.

Plurals of -ster formations are in –s, e.g. werksterscleaning ladies, winkelierstersfemale shopkeepers, martelaarstersfemale martyrs.

Geographical person names in -er or -aar never take -ster, so there is no *Antwerpenaarster next to Antwerpen-aarsomeone from the city of Antwerp or *Texelaarster next to Texel-aarsomeone from the isle of Texel, nor *Schiedamster next to Schiedam-ersomeone from the city of Schiedam or *Vlielandster next to *Vlieland-ersomeone from the isle of Vlieland. Instead, a derivation in -e from the pertinent adjective is used for the female inhabitant name: Antwerps-e, Texels-e, Schiedams-e, Vlielands-e.

Formations with the suffix -ster denote female person names: a schrijfsterfemale writer is the feminine counterpart of schrijverwriter. Some kind of professionalism or habit is often implied: not every woman who writes is a schrijfster. For deverbal -ster formations, the interpretation as Agent nouns is the default (e.g. schrijfsterfemale writer, someone who writes), but Theme interpretations occur as well (e.g. martelaarsterfemale martyr, woman who is tortured (to death)), completely parallel to the corresponding formations in -er, -aar, etc.

Regular diminutives are in -tje: werkstertje, winkelierstertje, martelaarstertje. Apart from diminutive formation, -ster formations cannot be input to further derivational processes. In compounds, they can, in principle, function both as left-hand and right-hand part as illustrated by verpleegstersuniformfemale nurse's uniform and ziekenverzorgsterfemale sick people's attendant, nurse, respectively. If they function as left-hand part, -ster formations are usually followed by a linking phoneme/s/. If a deverbal -ster formation functions as the right-hand part of a N-N compound, the left-hand part is interpreted by default as a (semantic) argument of the verb (see also compounding), e.g. Patient in ganzenhoedstergoose girl, woman who herds geese, Location in wereldreizigsterworld traveler.