 Finally, many feminine nouns that end in -η ("-i") correspond to Ancient Greek nouns in -ις ("-is"), which are still used as learned forms in formal contexts.Their singular forms have been adapted to the rest of the feminine nouns, while their plural forms have retained the ancient pattern in -εις ("-eis").The forms of the genitive singular -εως ("-eos") are also found as a stylistic variant and they are fully acceptable, and in fact are more commonly used than the old-style nominative singular form.