amor

Amor, amoris, m., third declension, built on amo with the -or suffix that turns verbs into abstract nouns: timeo gives timor, doleo gives dolor. The r of the stem is a rhotacised s, which is why the older spelling amos turns up in archaic texts.

The genitive is ambiguous and the ambiguity matters. Amor dei can be God's love for us or our love for God, and centuries of theology hang on which reading you take; Latin will not settle it for you, so the context has to. The word covers affection of every temperature, from family feeling to the ruinous passion of elegy, and when it is capitalised Amor is Cupid himself. Classical Latin also has caritas for a cooler, dutiful love, and the Vulgate's choice between the two is a translation decision, not a neutral one.