constancy n.

obsolete form of constancy, mid-14c., constaunce, "steadfastness, self-possession, composure," from Old French constance "steadfastness, permanence" (14c.), from Latin constantia "firm standing, steadiness, firmness, unchangeableness; firmness of character" (source of Italian costanza, Spanish constancia), abstract noun from present-participle stem of constare "to stand together" (see constant (adj.)). Obsolete since 17c. except as a given name for a girl (familiarly Connie), in which use it enjoyed a mild popularity in U.S. c. 1945-1955.

abstract noun suffix of quality or rank, from Latin -cia, -tia, from Greek -kia, -tia, from abstract ending -ia (see -ia) + stem ending -c- or -t-. The native correspondents are -ship, -hood.