Meaning of “senior” - Learner’s Dictionary

senior

adjective uk us /ˈsiːniər/
MORE IMPORTANT

B2 having a more important job or position than someone else:

a senior executive
We work in the same team but she's senior to me.
OLDER

older:

senior students
NAME (written abbreviation Sr) mainly US

used at the end of a man's name to show that he is the older of two men in the same family who have the same name:

Hello, may I speak to Ken Griffey, Senior, please?

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