Definition of defectivation in US English:

defectivation

noun

Linguistics
  • The fact of a marked inflectional category lacking certain features found in the corresponding unmarked category (e.g. the marked category of the future in French lacks a subjunctive, and is thus defective beside the present, which has both an indicative and a subjunctive); an instance of this.

Origin

1940s. From defective + -ation, after French défectivation (L. Hjelmslev, 1937 or earlier).

Pronunciation

defectivation

/dɪˌfɛktɪˈveɪʃn/