Origin: Latin suffix -ous
Spontaneous has 3 different meanings across 1 category:
happening or arising without apparent external cause
"spontaneous laughter"
"spontaneous combustion"
"a spontaneous abortion"
said or done without having been planned or written in advance
"he made a few ad-lib remarks"
Self-generated; happening without any apparent external cause.
"A spontaneous outburst of laughter from the crowd caught everyone off guard."
In plain English: Something spontaneous happens all by itself without any planning or outside help.
"The audience broke into spontaneous applause when the singer made a mistake and recovered with humor."
Usage: Use spontaneous to describe actions or events that occur naturally and unexpectedly, such as laughing at an inside joke or flowers blooming in spring. This word emphasizes the absence of planning rather than a lack of reason, distinguishing it from synonyms like accidental which imply unintended outcomes.
Learned borrowing from Late Latin spontāneus.