- bidirectional (adj.)
[bidirectional 词源字典]
- also bi-directional, 1941, from bi- + direction + -al (1). Originally of microphones. Related: Bidirectionally.[bidirectional etymology, bidirectional origin, 英语词源]
- omnidirectional (adj.)
- 1927, from omni- + directional (see direction).
- unidirectional (adj.)
- 1883, from uni- + directional (see direction).