spitzen
to sharpen
To sharpen something, usually a pencil, so that it gets a fine point.
Kannst du mir bitte den Bleistift spitzen?
Can you please sharpen the pencil for me?

to sharpen
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to sharpen
To sharpen something, usually a pencil, so that it gets a fine point.
Kannst du mir bitte den Bleistift spitzen?
Can you please sharpen the pencil for me?

The verb 'spitzen' (to sharpen / to make pointed) is derived from the noun 'die Spitze' (the point / tip). It describes the action of making something pointed or taking on a pointed shape.
Die Spitze des Turms ragte in den Himmel.
The tip of the tower rose into the sky.
The meaning of 'spitzen' becomes clear through the object in the sentence. You can 'spitzt' a pencil, the ears, or the mouth—each combination has its own fixed meaning.
Spitz bitte den Stift, er schreibt nicht mehr gut.
Please sharpen the pencil; it doesn't write well anymore.
In the literal meaning, 'spitzen' (to sharpen) is used almost exclusively for pencils. Typical objects are 'Bleistifte' (pencils) or 'Buntstifte' (colored pencils). The appropriate tool for this is called 'der Spitzer' (the sharpener).
Für die Zeichnung musste ich alle meine Buntstifte spitzen.
For the drawing, I had to sharpen all my colored pencils.
The expression 'die Ohren spitzen' (to prick up one's ears) is a fixed unit. It means that someone suddenly listens very attentively, often because they hear something unexpected or interesting.
Der Hund spitzte die Ohren, als er den Schlüssel in der Tür hörte.
The dog pricked up its ears when it heard the key in the door.
'den Mund spitzen' (to purse one's lips) is also a fixed expression. It describes the physical action of forming the lips into a round shape, typically to whistle, make a kissing mouth, or express doubt.
Das Kind spitzte den Mund, weil es das Gemüse nicht essen wollte.
The child pursed his lips because he didn't want to eat the vegetables.
to listen
'zuhören' and 'die Ohren spitzen' both have to do with listening attentively. 'zuhören' is the normal word when you consciously listen to what someone is saying and want to understand it. 'die Ohren spitzen' is a fixed expression and sounds more figurative. You use it when someone suddenly becomes especially attentive because something is interesting, important, or perhaps secret. 'zuhören' fits in almost all normal conversations. 'die Ohren spitzen' fits better when curiosity or special attention is the focus.

Nach der Nachricht haben die Gäste sofort die Ohren gespitzt.
After the news, the guests immediately pricked up their ears.
Beim Termin hören wir der Ärztin genau zu.
At the appointment, we listen carefully to the doctor.