Background<br /><br />Many adjectives (especially those that are compound) decline the same (often the 2nd declension) for M and F, and like 2nd neuter for N. Sometimes this is spoken of as "adjectives of two terminations" or "two endings."<br /><br />So, "deathless" [face=SPIonic]a)qa/natoj, -on[/face], because it is a compound (that a- bit at the front, meaning -less, along with the thanatos part), it only has two sets of endings: one for M and F, one for N. Thus, "The Deathless Muses" would be [face=SPIonic]ai( a)qa/natoi Mou=sai[/face].<br /><br />But you should think of these adjectives as sharing a single declension for both M and F, rather than thinking of them as taking masculine adjectives for feminine nouns. Keep in mind that the noun [face=SPIonic]no/soj[/face] "disease" is grammatically feminine, though it also takes the 2nd declension. Don't wed gender to declension too tightly - there are always exceptions.<br /><br />Homer regularly gives 2-ending adjectives a first declension feminine form when it suits him to do so. Other poets take similar liberties.<br /><br />These 2-ending adjectives survive in Attic, and in Koine, Greek. In the Koine you find more of them shifting allegiance to the 3-ending systems, but a quick look at my NT dictionary shows the 2-ending system was still robust.<br /><br />However<br /><br />While poets, imitating Epic diction, might have used 3-declension adjectives like 2-declension systems, I don't believe this practice existed in later Greek. Smyth gives no guidance except to say poets can do this, but that it does rarely occur in prose.