A Venusian one lasts eight Earth months (3)
I believe the answer is:
day
(Other definitions for day that I've seen before include "Dawn to dusk" , "Doris -, US actress" , "Unit of time" , "24 hour period" , "Born yesterday" .)
I believe the answer is:
day
(Other definitions for day that I've seen before include "Dawn to dusk" , "Doris -, US actress" , "Unit of time" , "24 hour period" , "Born yesterday" .)