According to a tantra:
- He stands for great compassion.
- Ru means the absence of gathering.
- Ka means not abiding in anything whatsoever.
In the Nyingma tradition, it is used as a general name for (male) wrathful deities. In the sarma schools of Tibetan Buddhism, Kagyü, Sakya and Geluk, heruka generally refers to Chakrasamvara and other chief deities of the mandalas of the Mother Tantras. The term Heruka can also be used to denote a realized tantric practicioner. 
- Padmasambhava & Jamgön Kongtrul, Light of Wisdom, Vol. 1 (Hong Kong: Rangjung Yeshe, 1999), p.64-65 & 170.