Declining the adjective "duplex"

Latin Learning Latin
1

This is an adjectival form with whose declension I am not yet familiar. The dictionary entry says “duplex, duplicis”; does that mean duplicis is the genitive, and duplex is the nominative through all the genders? Is it thus like felix?

I’m not familiar with declining adjectives like duplex, so can you tell me if this is correct:

SING.
Masc & Fem: duplex, duplicis, duplici, duplicem, duplici

Neut: duplex, duplicis, duplici, duplex, duplici

PL.
Masc & Fem: duplices, duplicium, duplicibus, duplices, duplicibus

Neut: duplicia, duplicium, duplicibus, duplicia, duplicibus

2

Correct, it declines like “felix.” These are third declension adjectives with one ending.