Alexander Gode & Hugh Blair IALA 1951
It may be important to note that the term "irregular second stem of verbs" as used in this grammar must not be allowed to conjure up the specter of verbal irregularities characteristic of most ethnic languages. In Interlingua the irregular second stem of verbs has nothing to do with matters of conjugation. It is a stem which occurs in certain derived nouns and adjectives and prevents these from assuming unnaturally distorted forms, as for instance scribitura instead of scriptura (from scriber), corrumpitive instead of corruptive (from corrumper), incidition instead of incision (from incider), etc. Furthermore the "regular" type, scribitura, corrumpitive, incidition, etc., need not be considered "wrong" but may be used whenever it seems stylistically possible or preferable.
In active word building it will be found that the irregular second stem occasions few difficulties but often simplifies the process of derivation. To derive, for instance, the "regular" form collidition from collider is not easy for anyone speaking as his native language English or any of the other languages of Western Civilization, while the use of the "irregular" stem collis- with a resulting collision seems natural and hence easy.
Finally one must not overlook the fact that active word building is in practice rarely a matter of deriving one word from another in a vacuum, so to speak, but rather a matter of fitting a new formation into a pattern of several familiar ones. To illustrate: Anyone needing an adjective to go with let us say extraher 'to extract,' will spontaneonsly coin extractive, not as the laborious result of attaching -ive to the verb but rather because extractive fits into the pattern of words already known, like extraher, extractor, extraction, extrahente. The new formation extractive is not - psychologically and pedagogically speaking - derived from an isolated extraher. It is fashioned from extraher in the presence of extraction, extractor, etc.
Every verb whose second stem does not result from the first by the simple addition of -at- or -it- is accompanied in the Interlinqua-English Dictionary by a full statement of its two stems. A descriptive survey of the irregular second stem of verbs may still be found useful for certain purposes and is attempted in the following paragraphs. Note that infinitives which do not appear in the Interlingua-Enqlish Dictionary are listed below within parentheses.
No derived verb can ever have an irregular second stem. Verbs like fusionar (from fusion), degrader (from grado), normalisar (from normal), falsificar (from false), blanchir (from blanc), etc. are always regular.
Compound verbs - whether formed with prefixes (componer, imprimer, interroger, etc.) or the compounding forms of full-fledged words (calefacer, benedicer, etc.) follow the pattern of the corresponding simple verbs in regard to regularity or irregularity of their second stems. Note that the stem vowel of verbs compounded with prefixes differs occasionally from the corresponding vowel of the simple verb, a phenomenon not to be preserved in active compounding. Such compounded verbs often recover or approach the original vowel- the vowel of the simple verb-in their irregular second stem.
(a: i/a) ager - ag-/act-; rediger - redig-/redact-
(a: i/e) facer - fac-/fact-; conficer - confic-/confect-
(e: i/e) leger - leg-/lect-; colliger - collig-/collect-
Verbs whose infinitive ends in -ar have an irregular second stem in only three exceptional instances.
Verbs whose infinitives end in -ir have an irregular second stem in the following exceptional instances:
All other verbs with irregular second stems have infinitives ending in -er. This statement cannot be reversed. Not all verbs ending in -er have irregular second stems. But cf. §148.
Verbs with infinitives in -er which have an irregular second stem can be grouped as follows:
When the first stem ends in c, l, n, p, r, u, x, the second stem is normally formed by the addition of t. Examples:
When the first stem ends in sc, this ending is reduced before the t added to form the second stem in the following examples:
Through the addition of t to form the second stem, the concluding sound (and spelling) of the first stem is normally affected as follows: b becomes p; g and h become c; m becomes mp; qu becomes cu; v becomes u. Examples:
In the following instances the final r of the first stem becomes an s before the t added to form the second stem:
When the first stem ends in d or t (also tt), the second stem is normally formed by changing these consonants to s or ss.
Similarly ct is changed to x. Examples:
In the following instances the second stem is formed by the addition of s to the first stem.
torquer: torqu-/tors-, tort-
The following verbs which belong in one or another of the preceding categories are further characterized by the suppression of m and n in the second stem:
Various irregularities not covered in the preceding categories appear in the following verbs:
offerer: offer-/offert-, oblat-
fluer: flu-/fluct-, flux-
fruer: fru-/fruct-, fruit-
poner: pon-/posit-, post-
prender: prend-/prens-, pris-
tender: tend-/tens-, tent-
torquer: torqu-/tort-, tors-
(tuer): tu-/tut-, tuit-
verter: vert-/vers-, -ors-
vider: vid-/vis-, vist-
volver: volv-/volut-, volt-