Father Tantra. One of the three main classes of anuttara-yoga-tantras, typified by the Guhyasamāja Tantra. Meditative practice (sādhana) based on the Father Tantras emphasizes the so-called ‘generation phase’ of visualization as a means of personal transformation.

A Dictionary of Buddhism, Oxford University Press, 2003, 2004 (which is available in electronic version from answer.com)