punctum indifferens
/ˌpʌŋ(k)təm ɪnˈdɪfərɛnz/noun
A neutral or common point; (also) a person who or thing which remains constant in changing circumstances.
Origin
Early 19th century; earliest use found in Samuel Taylor Coleridge (1772–1834), poet, critic, and philosopher. From classical Latin punctum + indifferēns indifferent.