Awesome, sick, great.
For decades the standard German youth word for "cool." "Geil!" on its own is enthusiasm; "affengeil" and "saugeil" intensify it. Older speakers may still hear the original meaning first.
Older meaning is sexually aroused — that sense still exists, which is exactly why the slang use surprises learners.
The original sense has not disappeared. Safe with friends; risky with your partner's grandmother.
Reading a definition isn't the same as saying it to someone. Lingo Kaiava is a voice tutor set to German — it uses geil the way locals do, corrects you in the moment, and never "fixes" the way real people actually talk into textbook German.
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