What is "acronychal"

Acronyc \A*cron"yc\, Acronychal \A*cron"ych*al\, a. [Gr. 'akro`nychos at nightfall; 'a`kros + ny`x night.] (Astron.) Rising at sunset and setting at sunrise, as a star; -- opposed to cosmical.

Note: The word is sometimes incorrectly written acronical, achronychal, acronichal, and acronical.