To find out definitely; to discover or establish. / (obsolete) To make (someone) certain or confident about something; to inform. / (archaic) To establish, to prove. / (archaic) To ensure or effect.

A bird that is not a songbird.

Not solicited; synonym of unsolicited (as used in the full name of the w:en:CAN-SPAM Act to make the backronym work)

(motor racing) Initialism of Indy Racing League.