There is nothing in the sources to suggest any defectiveness, strictly speaking, However, there are two archaic auxiliary/copula verbs which exist in residual form, performing a variety of functions. While it would be stretching it to construe them as inflected verb forms at the synchronic level, they are striking for the number of paradigmatic cells which have been preserved. When lined up and compared to a normal verb, they almost look like a (defective) paradigm. Below, these forms (taken from Beffa and Hamayon 1975 and Kullmann and Tserenpil 1996) are compared to the complete paradigm of a normal verb (taken from Svantesson 2003).
| normal verb 'laugh' |
residual auxiliary 1 bV- |
residual auxiliary 2 a- |
||
| finite | durative | inee-ne | ||
| terminative | inee-w | |||
| confirmative | inee-lee | bi-lee | ||
| resultative | inee-jee | a-jee | ||
| imperative | inee | |||
| prescriptive | inee-g-eerei | |||
| precative | inee-g-eec | |||
| voluntative | inee-ÿe | |||
| desiderative | inee-g-esei | |||
| permissive | inee-g | |||
| dubitative | inee-g-üüzei | |||
| potential | inee-mdz | |||
| participles | future | inee-x | bu-x | |
| imperfective | inee-g-ee | |||
| perfective | inee-sen | ag-san | ||
| habitual | inee-deg | |||
| agentive | inee-gc | |||
| converbs | modal | inee-n | ||
| imperfective | inee-j | a-j | ||
| perfective | inee-g-eed | be-g-eed | a-g-aad | |
| conditional | inee-wel | |||
| concessive | inee-wc | a-wc | ||
| terminative | inee-tel | be-g-eetel | a-tal |
There are also further relic forms of bV- and a- which are themselves archaic or unusual, having no direct correspondences in the paradigm of a normal contemporary verb.
Beffa, Marie-Lise, and Roberte Hamayon. 1975. Eléments de grammaire mongole. Paris: Dunod.
Kullmann, Rita and D. Tserenpil. 1996. Mongolian grammar. Hong Kong: Jensco.
Svantesson, Jan-Olof. 2003. Khalkha. In: Juha Janhunen (ed.) The Mongolic languages . London: Routledge. 154-176.