Same entry, according to Adler, in the Ambrosian Lexicon (1935); also in ps.-Herodian, Epimerismoi 73.15.
This form, first person singular present indicative/subjunctive active, is attested only in lexicography and grammars. LSJ (web address 1) claims that when the subject is female the active forms of this verb are synonymous with the more common medio-passive form kui/+skomai ('conceive', 'be impregnated'). There are some cases where this seems to be true (e.g. Galen 4.513), but others that are more ambiguous and may represent a more genuinely active meaning for the verb (in the sense of 'produce offspring'); e.g. Philo Judaeus, Life of Moses 1.13.2. LSJ also cites an instance with a male subject where the verb connotes 'impregnate'. This may be the usage the lexicographer has in mind, since the glossing verb gennw= is more common with a male subject ('beget' rather than 'give birth') when the context is the actual production of offspring and not metaphorical.