common

meaning in plain English

Seen or found in many places, not rare or special.

Think common = everywhere — pigeons are a common sight in cities.

for example

Both runners share the common goal of finishing first in the race.

When something is common, it’s not rare or special—it’s the kind of thing you see or hear about all the time. Like how a cough is common when everyone around you is sick, but a broken leg is not.