blank tape; blank video tape; blank audio cassette
Refers to a blank magnetic tape, either video or audio, that has not been recorded on. The term is somewhat dated, as physical tape media are less common today.
Back in the day, we used to record TV shows on blank video tapes.
This blank audio cassette can record for 120 minutes.
Compound of 生 (なま, 'raw' or 'unprocessed') and テープ ('tape'), literally meaning 'raw tape' or 'unrecorded tape'.