Noun
anceps (plural ancipites)
(poetry, Greek and Latin meter) A syllable that can be either short or long.
The experiment showed that G. anceps in particular can prey on all instars of both mosquito species and maintain a steady predation rate over time. Source: Internet
Evolution Uintatherium anceps Cladogram showing relations within Ungulata Perissodactyla and Artiodactyla include the majority of large land mammals. Source: Internet
Because of the anceps (a short or long syllable), the sixth foot can be filled by either a trochee (a long then short syllable) or a spondee. Source: Internet