Pokorny suggests a derivation, along with Aquilō (“the North wind”), from aqua;[1] De Vaan 2008 finds this preferrable to a derivation from aquila (“eagle”) adopted by Cohen 2004: 32.
aquilus (feminine aquila, neuter aquilum); first/second-declension adjective
First/second-declension adjective.
| singular | plural | ||||||
|---|---|---|---|---|---|---|---|
| masculine | feminine | neuter | masculine | feminine | neuter | ||
| nominative | aquilus | aquila | aquilum | aquilī | aquilae | aquila | |
| genitive | aquilī | aquilae | aquilī | aquilōrum | aquilārum | aquilōrum | |
| dative | aquilō | aquilae | aquilō | aquilīs | |||
| accusative | aquilum | aquilam | aquilum | aquilōs | aquilās | aquila | |
| ablative | aquilō | aquilā | aquilō | aquilīs | |||
| vocative | aquile | aquila | aquilum | aquilī | aquilae | aquila | |
| albus, candidus, subalbus, niveus, cēreus, marmoreus, eburneus, cānus, blancus (ML.) | glaucus, rāvus, pullus, cinereus, cinerāceus, plumbeus, grīseus (ML. or NL.) | niger, āter, piceus, furvus |
| ruber, rūbidus, rūfus, rubicundus, russus, rubrīcus, pūniceus, murrinus, mulleus; cocceus, coccīnus, badius | rutilus, armeniacus, aurantius, aurantiacus; fuscus, suffuscus, colōrius, cervīnus, spādīx, castaneus, aquilus, fulvus, brunneus (ML.) | flāvus, sufflāvus, flāvidus, fulvus, lūteus, gilvus, helvus, croceus, pallidus, blondinus (ML.) |
| galbus, galbinus, lūridus | viridis | prasinus |
| cȳaneus | caeruleus, azurīnus (ML.), caesius, blāvus (LL.) | glaucus; līvidus; venetus |
| violāceus, ianthinus, balaustīnus (NL.) | ostrīnus, amethystīnus | purpureus, ātropurpureus, roseus, rosāceus |