noun which may take the genitive case particle 'no'
non-volitional; involuntary; spontaneous; unintentional
Describes actions or states that occur without conscious will or intention. Often used in linguistics (e.g., 無意志動詞) and psychology.
「見える」は無意志動詞で、自分の意思ではコントロールできない。
'Mieru' is a non-volitional verb; you cannot control it by your own will.
くしゃみは無意志的な反応だ。
A sneeze is an involuntary reaction.
不随意 is a medical/biological term for 'involuntary' (e.g., muscles), while 無意志 is broader and used in linguistics and philosophy.
Compound of 無 (mu, 'without') and 意志 (ishi, 'will, volition'). The term is a direct negation of 意志, likely coined in academic contexts.