Lewis & Short

2. Quĭrīnus, a, um, adj. [1. Quirinus, I.], of or belonging to Quirinus, i. e. Romulus, Quirinal (poet.): spolia ex umeris Quirinis (al. Quirini), Prop. 4 (5), 10, 11: collis, i. e. the Quirinal, Ov. M. 14, 836.
Hence, as subst.: Quĭrīna, q. v.
And hence, perh., subst., the poet. appellation Quirinus, given to Augustus and Antony, cited under 1. Quirinus.