
1) Ad hoc 2) Impromptu 3) Impulsive 4) Instinctive 5) Intuitive 6) Middle of the resolution 7) Natural 8) Out of the blue 9) Self-generated 10) Unpremeditated 11) Unprepared 12) Unprompted
Found on
https://www.crosswordclues.com/clue/spontaneous

1) Ad-lib 2) Automatic 3) Autonomic 4) Free-hearted 5) Impetuous 6) Impulsive 7) Instinctive 8) Intuitive 9) Knee-jerk 10) Natural 11) Snap 12) Spur-of-the-moment 13) Ultroneous 14) Unbidden 15) Unexpected 16) Unplanted 17) Unprepared 18) Unprompted 19) Unscripted 20) Unwelcome 21) Voluntary
Found on
https://www.crosswordclues.com/clue/spontaneous

spontaneity; spontaneous process; spontaneous reaction. A spontaneous process occurs because of internal forces; no external forces are required to keep the process going, although external forces may be required to get the process started. For example, the burning of wood is spontaneous once the fire is started. The combination of water and carbon...
Found on
http://antoine.frostburg.edu/chem/senese/101/glossary/s.shtml

• (a.) Proceding from natural feeling, temperament, or disposition, or from a native internal proneness, readiness, or tendency, without constraint; as, a spontaneous gift or proportion. • (a.) Proceeding from, or acting by, internal impulse, energy, or natural law, without external force; as, spontaneous motion; spontaneous growth. &bull...
Found on
http://thinkexist.com/dictionary/meaning/spontaneous/
[Adjective] Something that happens on impulse or without planning.
Example: Spontaneous clapping broke out among the audience as the speaker finished his talk.
Found on
http://www.bbc.co.uk/skillswise/glossary/

1. Proceding from natural feeling, temperament, or disposition, or from a native internal proneness, readiness, or tendency, without constraint; as, a spontaneous gift or proportion. ... 2. Proceeding from, or acting by, internal impulse, energy, or natural law, without external force; as, spontaneous motion; spontaneous growth. ... 3. Produced wit...
Found on
http://www.encyclo.co.uk/local/20973
Spon·ta'ne·ous adjective [ Latin
spontaneus , from
sponte of free will, voluntarily.]
1. Proceding from natural feeling, temperament, or disposition, or from a native internal proneness, readiness, or tendency, without constraint; as, a
spontaneous gift or proportion.
...Found on
http://www.encyclo.co.uk/webster/S/171

Said of plants that have escaped from cultivation, but that do not permanently persist.
Found on
http://www.gardenology.org/wiki/Glossary_of_Gardening_Terms

Type: Term Pronunciation: spon-tā′nē-ŭs Definitions: 1. Without apparent cause; said of disease processes or remissions.
Found on
http://www.medilexicon.com/medicaldictionary.php?t=84063

[
adj] - happening or arising without apparent external cause
Found on
http://www.webdictionary.co.uk/definition.php?query=spontaneous
adjective happening or arising without apparent external cause; `spontaneous laughter`; `spontaneous combustion`; `a spontaneous abortion`
Found on
https://www.encyclo.co.uk/local/20974
[SAT terms] said or done without having been planned in advance
Found on
https://www.vocabulary.com/lists/158007
No exact match found.