What is "jamadagni"

In Hindu mythology, Jamadagni (or Jamdagni, ) is one of the Saptarishis (Seven Great Sages Rishi) in the seventh, current Manvantara. He is the father of Parashurama, the sixth incarnation of Vishnu. He was a descendant of the sage Bhrigu, one of the Prajapatis created by Brahma, the God of Creation. Jamadagni had five children with wife Renuka, the youngest of whom was Parashurama, an avatar of Lord Vishnu. Jamadagni was well versed in the scriptures and weaponry without formal instruction.