noun which may take the genitive case particle 'no'
omnidirectional; nondirectional
Technical term used mainly for microphones, antennas, and similar devices that pick up or radiate equally in all directions.
このマイクは無指向性なので、周囲の音を均等に拾います。
This microphone is omnidirectional, so it picks up surrounding sounds evenly.
指向性 means 'directional' (having a preferred direction), while 無指向性 means 'omnidirectional' or 'nondirectional'.
Compound of 無 (mu, 'without') + 指向性 (shikōsei, 'directivity'). The exact historical derivation is uncertain, but the word follows standard Sino-Japanese word formation.