Meaning of “bug” - Learner’s Dictionary

bug

noun [ C ] uk us /bʌɡ/
ILLNESS

B2 a bacteria or virus, or the illness that it causes:

a flu / stomach bug
COMPUTER

B2 a mistake in a computer program:

This program is full of bugs.
INSECT
EQUIPMENT
be bitten by the bug/get the bug informal

to develop a strong interest or enthusiasm for a particular activity:

He's been bitten by the tennis bug.

(Definition of “bug noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)