What is the meaning of Defective?

Having one or more defects.

Lacking some forms; e.g., having only one tense or being usable only in the third person.

Having a root whose final consonant is weak (ي, و, or ء).

Not capable of representing all the phonemic distinctions of a language it is used to write.

Spelled without matres lectionis, for example אמץ (ómets, courage) as opposed to the plene spelling אומץ where the letter vav ⟨ו⟩ indicates the vowel o.

Without matres lectionis (letters indicating vowels) written out.

A person or thing considered to be defective.

A word written without matres lectionis (letters indicating vowels).

defective (having defects)

vocative masculine singular of dēfectivus

Source: wiktionary.org