a human written or spoken language used by a community; opposed to e.g. a computer language
"The teacher asked students to speak their native tongue rather than using English on the test."
the tongue of certain animals used as meat
"We ordered grilled beef tongue at the restaurant to try the tender, savory delicacy."
the flap of material under the laces of a shoe or boot
"He pulled down the stiff tongue of his hiking boots to ensure his foot stayed secure inside."
The flexible muscular organ in the mouth that is used to move food around, for tasting and that is moved into various positions to modify the flow of air from the lungs in order to produce different sounds in speech.
"He quickly pulled his tongue out to clean a piece of candy stuck between his teeth before speaking again."
In plain English: The tongue is the muscular part inside your mouth that helps you taste food and speak words.
"She stuck out her tongue at him when he got in trouble for breaking the rules."
Usage: Use "tongue" for the muscular organ in your mouth that helps you taste and swallow food. In music contexts, it refers to the action of striking air against the roof of the mouth to start a note on wind instruments.
articulate by tonguing, as when playing wind instruments
"The clarinetist articulated rapid staccato notes by tonguing sharply against the reed."
lick or explore with the tongue
"The curious puppy stretched out its neck to lick and explore the salty air on his owner's hand."
On a wind instrument, to articulate a note by starting the air with a tap of the tongue, as though by speaking a 'd' or 't' sound (alveolar plosive).
"The musician rolled his 'r's and tongued each sharp note on the trumpet."
In plain English: To tongue means to move your mouth around so that it looks funny, often while making silly noises with your lips and teeth.
"She stuck out her tongue to lick the ice cream off the spoon."
A surname​.
"The Tongue family has lived in that small village for three generations."
The word "tongue" comes from Old English tunge, which traces back to a Proto-Indo-European root meaning "tongue." It is also a doublet of the word "language," sharing the same ancient origin.