a.

1. 【電】單極的
2. 【生】（指神經細胞）單尾的；單極的

adj.

1. having or relating to a single pole or extremity.
   ▸Electronics  (of a transistor or other device) using either negative or positive charge carriers but not both.
2. (of psychiatric illness) characterized by either depressive or manic episodes but not both.
3. (of a nerve cell) having one axon.