noun

• (dated) A stammering speech disorder, in which the /n/ sound is given to other consonants.
  "Not only in formal discourse, but in the ordinary walks of life, a well-modulated, expressive voice is a most valuable asset, whether one’s object be to interest, persuade or convince, to give a command or entreat a favor. The moulding of the voice into finished articulate speech is a mechanism in which the entire oral cavity, including palate, teeth, tongue and lips, take an important part. As a result of either structural defect of these organs, or, as is more often the case, as a consequence of their imperfect innervation, various logopathies may occur, which profoundly affect the social status of the unfortunate individual and seriously embarrass his way to a successful career. Lisping, stuttering, stammering, lallation, nunnation, and sigmatism, paragammacism and paralambdacism are but few of the locutory evils encountered, much too frequently in adolescents and adults. The fact that they are mostly amenable to treatment and may often be completely corrected, with proper attention and training, is something that needs to be more thoroughly impressed upon our educational bodies and sociologic reformers."
• (archaic, rare) An inclination of Germanic languages to employ -n in endings.
  "§ 146. The two important exceptions to the rule that the Frisian agrees with the Westsaxon rather than with the Northumbrian are the two connected with its Phonesis; in respect to (1) its Nunnation and (2) its Sigmatismus. It has less of both than the Westsaxon; though the absence of neither is quite so conspicuous as it is in the Norse. § 147. Eschewal of the Nunnation; Change from -an to -a.—This we find in three inflections: a. In the Weak (or Simple) Substantive—A. S.; eágan = eye’s and eyes, &c.; tungan = tongue’s and tongues, &c.; naman = name’s and names &c.—in Frisian ága, tunga, nama, &c. b. In the Definite Adjective—A. S. gódan = boni, bonæ, bono, in the Singular; and boni, bonæ, bona, bonos, &c., in the Plural. In Frisian the form is góda. c. In the Infinitive Mood of Verbs — A. S. deman = judicare, bærnan = urere, &c.; in Frisian, dema, berna, &c. In all these the Northumbrian agrees with the Frisian, and both with the Norse."