reaction
n. C / Un. something you say, do, or feel because of something else that happened. It can also be a chemical change when two substances are mixed together.
n. a response to a stimulus, event, or situation; in chemistry, the process where substances interact to undergo chemical change.
His reaction to the news was a big smile.
The government's sudden policy change caused a strong negative reaction from the public and local business owners.
While the initial chemical reaction produced a significant amount of heat, the secondary phase required a catalyst to ensure the compound remained stable at room temperature.
Inherited from Middle English reaccion, from Old French reaction, from Latin reāctiō, from the verb reagō, from re- (“again”) + agō (“to act”); more at re-, action; equivalent to react + -ion.
Countable when referring to a specific response or chemical event; uncountable when referring to the general process of reacting.
What was your reaction about the movie?What was your reaction to the movie?The noun reaction typically takes the preposition 'to' rather than 'about' when describing a response to something.