Irrational anger- Anger aroused only on account of the rise of krodhavedanīya (anger-experiencing) Karma without any external stimulation.
apratiṣṭhito nāma yadaiṣa svayaṃ duṣkaraṇamākrośādikaṃ ca kāraṇaṃ vinā nirālambana eva kevalakrodhavedanīyādupajāyate.
(Prajñā 14.3 Vṛ Pa 290)