What is "tilopa"

Tilopa ( Prakrit; Sanskrit: Talika or Tilopada) (988–1069) was born in either Chativavo ( Chittagong), Bengal or Jagora, Bengal in India. He was a tantric practitioner and mahasiddha. He practiced Anuttarayoga Tantra, a set of spiritual practices intended to accelerate the process of attaining Buddhahood. Naropa is considered his main student.