die Zunge
tongue
The movable, muscular organ in the mouth that is used for tasting, swallowing, and speaking.
Der Arzt sagte mir, ich solle die Zunge herausstrecken.
The doctor told me to stick out my tongue.

tongue
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tongue
The movable, muscular organ in the mouth that is used for tasting, swallowing, and speaking.
Der Arzt sagte mir, ich solle die Zunge herausstrecken.
The doctor told me to stick out my tongue.

In connection with the body part, 'Zunge' (tongue) is often used in fixed collocations. Common ones are 'sich auf die Zunge beißen' (to bite one's tongue, also figuratively) and 'die Zunge herausstrecken' (to stick out one's tongue).
Ich wollte etwas Unhöfliches sagen, habe mir aber gerade noch auf die Zunge gebissen.
I wanted to say something rude, but I managed to bite my tongue just in time.
The expression 'etwas liegt einem auf der Zunge' (something is on the tip of one's tongue) always uses the dative for the person. So it is 'es liegt MIR auf der Zunge', not 'ich'.
Warte, sag es nicht! Der Name liegt mir auf der Zunge.
Wait, don't say it! The name is on the tip of my tongue.
The expression 'sich die Zunge verbrennen' (to get burned by saying something inappropriate) is reflexive. You must use the appropriate reflexive pronoun in the dative: ich verbrenne MIR, du verbrennst DIR, er verbrennt SICH die Zunge.
Sei vorsichtig, was du im Meeting sagst, damit du dir nicht die Zunge verbrennst.
Be careful what you say in the meeting so you don't get burned.
The use of 'Zunge' (tongue) for 'Sprache' (language) is elevated or poetic. In normal everyday language, the word 'Sprache' is almost always used.
Der Dichter beherrschte mehrere Zungen.
The poet mastered several tongues.
You will always recognize this specific, technical meaning from the context. If a 'Gürtel' (belt), 'Schnalle' (buckle), or 'Verschluss' (clasp/fastener) is mentioned, this small metal part is meant.
Die Zunge der Gürtelschnalle ist aus Messing.
The tongue of the belt buckle is made of brass.
language
'Sprache' and 'Zunge' are both connected with speaking. 'Sprache' normally means the system of words and grammar, for example German or Spanish, or also the style in which someone speaks or writes. 'Zunge' is first of all the organ in the mouth that you use to speak, taste, and swallow. In a figurative or elevated meaning, 'Zunge' can also mean 'language' or manner of speaking, but this is much rarer in everyday language. Learners may confuse the words because both are connected with speaking. In practice: for German, English, or a way of speaking, you almost always use 'Sprache'; for the body part, you use 'Zunge'.

Nach dem heißen Tee hat mir die Zunge wehgetan.
After the hot tea, my tongue hurt.
In der Klasse lernen viele Schüler eine neue Sprache.
Many students in the class are learning a new language.