"cerrar herméticamente" in English

to cap off- to close up- to slam- to block up- to cast off- to close off- to conclude- to double- to fasten- to fasten- to fasten down- to fold- to fold up- to go out- to lock up- to seal up- to seal up- to shut up- to shut up- to tie up- to wind up- to wind up- to zip up- to shut down- to close- to shut- to chock- to clinch- to lock- to pull down- to seal- to seal off- to turn off- to bring … to an end- to end- to bring up the rear of- to button up- to do upto clench- to draw- to fence off- to finalize- to lower- to put … down- to put the cork in- to put the top on- to put the lid on- to put the top on- to sew up- to shut off- to close down- to block- to do up

hermetically

airtight- hermetic- inscrutable- secretive