How acceptable is to use the word "dorsal" as antonym for "lateral"? Are there better antonyms denoting direction along the vertical as opposed to lateral.
dor·sal (dôr′səl) adj. 1. Anatomy Of, toward, on, in, or near the back or upper surface of an organ, part, or organism. 2. Botany Of or on the surface of an organ or part facing away from the axis; abaxial.
This is not the word you are looking for, as it refers to a location on a physical object or thing, such as a fish (e.g. dorsal fin).
Try upright or perpendicular.
ver′ti·cal·ly adv. Synonyms: vertical, upright, perpendicular, plumb. These adjectives mean being at or approximately at right angles to the horizon or to level ground. Vertical and upright are often used to signify contrast with what is horizontal: wallpaper with vertical stripes; an upright column. Perpendicular and plumb are generally used to specify an angle of precisely 90 degrees: a perpendicular escarpment; careful to make the doorjambs plumb.
"Dorsal" pairs with its antonym "ventral". In anatomy broadly dorsal on the back / spine side, ventral on the abdominal / belly side.
In anatomy "Lateral" is best paired with the antonym "medial" and relates to longitudinal axis from head to to tail. More medial is closer to the midline, more lateral, away from midline.
Ventral is directional. For example the palm of the hand is considered ventral and the "back" of the hand, dorsal.
I get the impression you are wanting to use dorsal for something non-anatomical (but you don't state what). It doesn't seem a good fit (as derives from latin dorsum meaning "back") to use it for things that can't be considered to have a backs, top sides / undersides.
If you just want to indicate above / below, then "superior" / "inferior" might be more suitable.