n. (context Welsh grammar English) A (l en verb) form which acts as a (l en defective) noun, having functions similar to the English (l en infinitive) and (l en gerund), and the Latin (l en supine).
A verbnoun is the basic form of a verb in Celtic languages such as Welsh, and is the form usually listed in the dictionary. It is the verb form which functions as a noun, naming an "action or state without reference to who does it or when". As such, it is usually used with an auxiliary verb.
It is formed by the addition of a suffix to a verb stem, though its form is sometimes the same as that of the verb stem. For example, in the Manx language, "etl" is the verb stem (and imperative singular, as is usually the case in Celtic languages) corresponding to the English verb " fly". The verbnoun is formed by the addition of the suffix "-agh" to this stem, giving "etlagh".