[ spɒn'teɪnɪəs ]
■ adjective
1》 performed or occurring as a result of an unpremeditated inner impulse and without external stimulus.
↘(of a process or event) occurring without apparent external cause.
↘ Biology (of movement or activity) instinctive or involuntary.
2》 open, natural, and uninhibited.
3》 archaic (of a plant) growing naturally and without being tended or cultivated.
Derivatives
spontaneity spɒntə'neɪɪti noun
~ly adverb
Origin
C17: from late L. spontaneus (from (sua) sponte 'of (one's) own accord') + -ous .