-eer/ɛ:r/ and its allomorphs is one of the four verbalizing suffixes in Dutch, and the only one that is productive; it belongs to the non-native stratum of the language. The others are -el, -er, and -ig; other verbs enter the language through borrowing or conversion. Bases are usually non-native nouns, adjectives or bound forms. Haas (1993: 348-351) distinguish three types:

• (4.5.1.1.) The suffix -eer often occurs with bound forms that are usually non-native, most often of Latin of French origin. Examples are producerento produce, to reside, concluderento conclue, emanciperento emancipate, procederento litigate, docerento teach, resumerento summarize, absorberento absorb, reagerento react, monterento mount, to assemble, fingerento feign, specificerento specify, refererento refer, masturberento masturbate, tatoeërento tattoo, variërento vary, riskerento risk, chaufferento drive. The distinction between Latin stems and others is relevant in that in Latin stems, /k/ before the suffix (usually spelled <c>) becomes /s/ (usually spelled <c>): specificerento specifyspecificatiespecification, abdicerento abdicateabdicatieabdication, implicerento implyimplicatieimplication, introducerento introduceintroductieintroduction, complicerento complicatecomplicatiecomplication. Another feature of these Latin stems is that they usually need additional material to become a word: the Latin stem dic-to point, e.g., cannot function as a verb wit -eer alone: another element (usually a bound form) is needed as well, as in indicerento indicate or abdicerento abdicate; the same holds for fic-to make in unificerento unify, simplificerento simplify, pacificerento pacify, etc. There is also a small group of roots ending in /k/ that are (probably) not of Latin origin where this alternation does not occur: frankerento frank, to prepay, markerento mark, maskerento mask, to camouflage and riskerento risk.
• (4.5.1.2) The suffix -eer can also be attached productively to nouns, usually non-Germanic ones: alarmerento alarm (cf. alarmalarm), balancerento balance (cf. balansbalans), triomferento triumph (cf. triomftriumph), spionerento spy (cf. spionspy), signalerento signal (cf. signaalsignal), duellerento duel (cf. duelduel), adviserento advise (cf. adviesadvice), importerento import (< importimport), portretterento portray (cf. portretportrait). If the noun ends in schwa, the schwa is deleted as a consequence of prevocalic schwa-deletion: coderento encode (cf. codecode), nuancerento nuance (cf. nuancenuance), annoncerento announce (cf. annonceannouncement), frauderento defraud (cf. fraudefraud), charmerento charm (cf. charmecharm). Sometimes the suffix also attaches to native nouns that are either monosyllabic (groeperento group, shockerento shock, normerento normalize, scalperento scalp, kamperento camp) or bisyllabic with schwa in the second syllable (redenerento reason < redenreason, waarderento value < waardevalue). If the noun ends in a vowel other than schwa, it is sometimes deleted (torpederento torpedo cf. torpedtorpedo, girerento indorse cf. girogiro, agenderento agenda cf. agendaagenda, diplomerento certificate cf. diplomadiploma, fantaserento imagine cf. fantasiephantasy), and not in other cases (parodiërento parody, tatoeërento tattoo). The suffix -eer also combines with non-native complex words: enthousiasmerento enthuse (enthousiasme is formed with -asme), urinerento urinate (urine contains -ine), reglementeren (reglement contains -ment), motiverento motivate (< motief containing -ief), telefoneren (telefoontelephone contains the bound form -foon), filosoferento philosophize (< filosoofphilosopher with the bound form -soof), telegraferento telegraph (< telegraaf telegraph contains the bound form -graaf). In other cases, a suffix or bound form may or may not be retained, e.g. with -ade: kwadraatsquare > kwadraterento square vs plagiaatplagiarism > plagiërento plagiarize. The final /k/ of the suffix -iek changes into /s/ (spelled <c>) when -eer is attached (specifiekspecific/specificerento specify, muziekmusic/musicerento play music); this does not work for other cases of final /k/: shockerento shock, blokkerento block, flankerento flank, etc. If a noun ends in the sequence consonant+schwa+/r/, registrerento register (cf. registerregister), filtrerento filter (cf. filterfilter), etc.
• (4.5.1.3) The suffix -eer attaches much less easier to adjectives, but we do find non-native stems (frequenterento frequent < frequentfrequent(ly)) as well as native ones (kleinerento humiliate < kleinsmall, halverento halve, to bisect < halfhalf). If the adjective ends in schwa, it is deleted: liquiderento liquidate < liquideliquid, validerento validate < validevalid, disambiguerento disambiguate (cf. ambigueambiguous). If the base is formed with a non-native suffix, the allomorph -iseer is often found: legaliserento legalize (< legaallegal), criminaliserento criminalize (< crimineelcriminal, populariserento popularize (< populairpopular).

Morphological potential: nominalizations of verbs in -eer are usually formed with non-native suffxes via affix substitution: the nominalizing suffixes do not come after the -eer suffix but replace it: e.g adviseuradvisor (cf. adviseerto advise with the -eur), plagiatorplagiarist (cf. plagieerto plagiarize and plagiaatplagiate) and filtratiefiltration (cf. filtreerto filter with the suffix -atie). In the case of the allomorphs of the suffix, only the -eer part is replaced: ioniseerto ionize > ionisatieionization, accentueerto accentuate > accentuatieaccentuation, which might be taken as an argument for stem allomorphy rather than affix allomorphy.