1) Dorsal 
the side away from the axis, for instance the lower surface of a leaf.
away from the axis, referring to the surface of an organ that is furthest from the axis in bud. cf. adaxial
a surface that is turned to face the base instead of towards the apex
Directed away from the stem of a plant; pertaining to the lower surface of a leaf. 
• (a.) Alt. of Abaxile
The surface or side of an organ directed away from the axis (usually the lower side).
The underside when referring to a leaf, or more specifically the side of the organ facing away from the stem (axis).
<botany> Describes a plant part which is on the side or surface of an organ, facing away from the axis. ... (09 Oct 1997) ... 
The leaf surface facing away from the stem of the plant.
Ab·ax'i·al (ăb*ăks'ĭ* a l), Ab*ax'ile (ăb*ăks'ĭl) adjective [ Latin ab + axis axle.] (Botany) Away from the axis or central line; eccentric. Balfour. 
Type: Term Pronunciation: ab-ak′sē-ăl, -ak′sīl Definitions: 1. Lying outside the axis of any body or part. 2. Situated at the opposite extremity of the axis of a part.
a surface that is turned to face the base instead of towards the apex
In botany, the term abaxial describes something facing away from the axis, such as the surface of a leaf for example.
[adj] - situated away from the axis of any body or part 2. [adj] - (biology) facing away from the axis of an organ or organism
Rays of light which do not coincide with the optical axis of a lens system. See also: Lens.
adjective facing away from the axis of an organ or organism; `the abaxial surface of a leaf is the underside or side facing away from the stem`
being or situated away from the axis: the abaxial surface of a leaf.