1. someone who conducts themselves in a frank and honest way
I like him/her, he/she's a real straight shooter
A 'straight shooter' is a person who conducts themselves in an honest and upright way, someone who is straightforward and direct. "He is a straight shooter, he always says what he means and means what he says." "You should ask Ava for her opinion, she's a straight shooter, she won't lie to you." This is an informal expression.