earplug (for protection against noise or water)
stopcock (gas, water); main valve; main tap; stop tap
cork stopper; (bottle) cork
nasal plug; wedge (in tusk mortise-and-tenon joint); wooden pin driven through tenon to hold it in place
unstopping; uncorking; uncapping; connecting (e.g. gas supply)
wooden plug; cork; tampion
stop cock; stop valve; curb cock; shut-off valve
rubber stopper; rubber plug
inner plug (bottle, etc.)
tonsillolith; tonsil stone
castor aralia (Kalopanax septemlobus); prickly castor oil tree