1 seal /ˈsiːl/ verb
seals; sealed; sealing
1 seal
seals; sealed; sealing
Learner's definition of SEAL
[+ object] : to close (something) tightly so that air, liquid, etc., cannot get in or out often + up
[+ object] : to close (an envelope, bag, etc.) by sticking or pressing two of its parts together
[no object] : to become closed tightly
[+ object] : to cover the surface of (something) with a substance that will protect it
[+ object] : to make (something) definite and final
[+ object] : to prevent someone from going into or through (an area or place)

my lips are sealed

see lip

seal in

[phrasal verb]
seal (something) in or seal in (something)
: to prevent (something that is in something else) from getting out or escaping

seal off

[phrasal verb]
seal off (something) or seal (something) off
: to prevent people from entering or leaving (an area or place)
2 seal /ˈsiːl/ noun
plural seals
2 seal
plural seals
Learner's definition of SEAL
: an official mark that is stamped on paper or on a small piece of wax to show that something (such as a document) is genuine and has been officially approved
: a small piece of stamped wax or a small sticker that is put on a letter or envelope to keep it closed or to show that it has not been opened
: a device with a raised design that can be pressed into something (such as paper or wax) to make a seal
: a piece of material (such as rubber) that is used on the lid of a container to keep air, water, etc., out of the container or to show the container has not been opened
: the state of being closed tightly so that no air, water, etc., can pass through

seal of approval

: an action or statement that shows approval or official acceptance

set the seal on

British, formal
: to make (something) final or definite

under seal

law, formal
: having an official seal that prevents the public from seeing or reading it
compare 3seal
3 seal /ˈsiːl/ noun
plural seals
3 seal
plural seals
Learner's definition of SEAL
[count] : a large animal that lives in the sea near coasts, has flippers, and eats fish
[noncount] : the skin of a seal usually used for fur
compare 2seal