clear free unblock unclog unplug unstop advance aid allow assist encourage facilitate forward help open permit promote release support unseal loosen continue begin start loose liberate delay refuse expand empty unload unburden unloose extricate ameliorate disengage cleanse clean purge declutter conceal uncork hide withhold evacuate drain exhaust vacate void deplete deprive pass approve enact ratify sanction accept authorise authorize constitute decree establish legislate legalise legalize validate endorse mouth opening beginning hole gap vent break split aperture outlet orifice breach chink perforation cleft puncture