Lacking + or -, electrically

• Like hydra neurons
• Lacking axial extremities, as nerve cells
• Like some nerve cells
• Having no radiating processes, as nerve cells
• Lacking direction, electrically
• Like nerve cells with no radiating processes
• Having no axes

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Apolar \A*po"lar\, a. [Pref. a- + polar.] (Biol.) Having no radiating processes; -- applied particularly to certain nerve cells.

Wiktionary Word definitions in Wiktionary
a. 1 Having no polarity 2 # (context chemistry physics English) Having no dipole 3 (context geometry English) Orthogonal under the polar pairing between the symmetric algebra of a vector space and its dual.