Faculty = Power of mind or physical or natural ability to hear, see, think, move, etc. (in this case plural ‘faculties’ is possible as the case may be)

• Prof. Thomas has a great faculty for learning languages.
• Even at the age of 90 he still had all his faculties.
• The mental faculties.

BUT never use faculties in the following cases.

A) Faculty = The whole teaching staff of a University or department such as the Faculty of Law/Science.

• The principal convened the meeting of the faculty ( NOT faculties)
• He is a faculty member in the Department of Electronics.

B) Faculty = a specific academic department in University or College.

• The faculty of history/Mathematics.