1. (n.) One who testifies under oath, especially in writing; also a verb of active meaning but passive or middle form\.

2. (n.) A deponent verb.

3. (a.) Having a passive form with an active meaning, as certain Latin and Greek verbs.

TV-viewer abutter adjoiner attestant attestator attester beholder bird-watcher borderer cojuror compurgator deponent drugstore cowboy earwitness eyewitness gaper gazer gazer-on girl-watcher goggler immediate neighbor informant informer kibitzer looker looker-on neighbor neighborer observer ogler onlooker passerby perceiver percipient seer sidewalk superintendent spectator spectatress spectatrix swearer tangent televiewer television-viewer testifier video-gazer viewer voucher watcher witness