From bi- +‎ directional.

• IPA^(key): /ˌbaɪ.dɪˈɹɛk.ʃə.nəl, -daɪ-/

• Audio (Southern England):

  (file)

• Hyphenation: bi‧di‧rec‧tion‧al

bidirectional (not comparable)

1. Moving in two directions (usually opposite).
2. Operating or functioning in two directions (usually opposite).
   • 2024 February 27, Andrew G. Thomas, “Incels Uncovered: How Potent Is the Black Pill?”, in Psychology Today‎^[1]:

     However, statistical modelling paints a different picture. We found that the influence of mental health and ideology on harmful attitudes and beliefs was two-and-a-half times stronger than networking. We also found that mental health and ideology shared a potential bidirectional relationship, with poor mental health causing greater buy-in to ideology and vice versa.

• unidirectional

bidirectional (plural bidirectionals)

1. Such an antenna or microphone