plural compounds
1
: something that is formed by combining two or more parts
especially, technical
: a substance created when the atoms of two or more chemical elements join together
chemical/organic compounds
a compound of sodium and chlorine
The metal reacts with the gas to form a compound.
2
: a word formed by combining two or more words
"Rowboat," "high school," and "light-year" are compounds.
compounds; compounded; compounding
1
: to make (something, such as an error or problem) worse : to add to (something bad)
He compounded [=exacerbated] his mistake by announcing it to the whole table.
2
finance
: to pay interest on both an amount of money and the interest it has already earned
The interest is compounded at regular intervals.
The interest compounds quarterly.
3
: to form (something) by combining separate things
compound a medicine
—usually used as (be) compoundedan attitude compounded of [=made up of] equal parts greed and arrogance
1
: made up of two or more parts
a compound leaf
a compound microscope
2
a
: made by combining two or more words
"Steamboat" is a compound noun.
b
: consisting of two or more main clauses
"I told him to leave and he left" is a compound sentence.
plural compounds
: an enclosed area that contains a group of buildings
a prison compound
Cite this Entry
“Compound.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/compound. Accessed 16 Apr. 2026.
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