LATIN DICTIONARYLexicon Latīnum
nounsecond declension

vicārius Chrīstī

vicārius Chrīstī m (genitive vicāriī Chrīstī)

Meaning

  1. EcclesiasticalLatinVicar of Christ, the pope
    […] et quod Spiritus sanctus in conciliis, vel vicarius Christi facit, Christus facere dicitur.[…] and what the Holy Spirit in the councils or the Vicar of Christ does, is said to be done by Christ.1562, Diego Laynez, Disputatio de origine jurisdictionis episcoporum et de Romani pontificis primatu, III.2.3.168:

Origins

See vicārius (“substitute, deputy”), Chrīstus (“Christ”). First attested as a papal epithet in the Roman Synod of 495, but applied literally to bishops, the apostles, and Frankish kings through the Early Middle Ages. Restricted to the pope from at least the 13th century.

Quick answers

What does vicārius Chrīstī mean in Latin?
vicārius Chrīstī, a noun, means “Vicar of Christ, the pope”.
What is the genitive of vicārius Chrīstī?
The genitive singular is vicāriī Chrīstī. vicārius Chrīstī is second declension.