rasieren
to shave
To remove body hair, especially beard hair, directly at the surface of the skin using a sharp blade or an electric device.
Er rasiert sich jeden Morgen gründlich.
He shaves thoroughly every morning.

to shave / crush / rip off
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to shave
To remove body hair, especially beard hair, directly at the surface of the skin using a sharp blade or an electric device.
Er rasiert sich jeden Morgen gründlich.
He shaves thoroughly every morning.

The context makes the meaning clear. If it is about personal grooming, the literal meaning is intended. In the context of a competition or game, it means 'besiegen' (to defeat). If it is about money or business, it often means 'betrügen' (to cheat).
Ich muss mich noch schnell rasieren, bevor wir gehen.
I still have to shave quickly before we go.
In its main meaning, 'rasieren' (to shave) is very often used reflexively: 'sich rasieren' (to shave oneself). If a specific body part is named, it appears in the accusative.
Er rasiert sich jeden Morgen vor dem Spiegel.
He shaves in front of the mirror every morning.
The meaning 'jemanden besiegen' (to defeat someone) is colloquial and belongs especially to youth slang. It is often used in the context of video games, sports, or competitions.
Im Online-Match hat sie ihren Gegner total rasiert.
In the online match, she totally crushed her opponent.
The meaning 'jemanden betrügen' (to cheat someone) is also colloquial. It is often used in the passive ('rasiert werden' — to get ripped off) to express that someone lost money or was taken advantage of.
Beim Autokauf wurde er komplett rasiert und hat viel zu viel bezahlt.
He got completely ripped off when buying the car and paid far too much.
to hit / beat
'schlagen' and 'rasieren' can both mean that you defeat an opponent. In this meaning, 'schlagen' is the normal word for sports, games, or competitions. 'rasieren' is very colloquial and means that the opponent is defeated especially clearly and overwhelmingly. Learners may confuse the words because both can fit in a game. If you want to speak neutrally, use 'schlagen'. 'Rasieren' fits more in casual conversations and sounds stronger.

Im Finale rasierte das Team den Gegner mit 6:0.
In the final, the team crushed their opponent 6–0.
Anton schlug seinen Freund beim Schach nach nur zwanzig Minuten.
Anton beat his friend at chess after only twenty minutes.