Lewis Short
(adjective) : per-grātus, a, um
* Very agreeable, very pleasant (class.): litterae,Cic. Q. Fr. 3, 1, 6, § 23: id mihi pergratum perque jucundum erit,id. ib. 3, 1, 4, § 12; id. Att. 10, 4, 1: pergratum mihi feceris, si,you would do me a great pleasure, a great favor,id. Lael. 4, 16.—In tmesi: per mihi, per, inquam, gratum feceris, si, etc.,Cic. Att. 1, 20, 7.
Charlton T. Lewis, Charles Short, A Latin Dictionary