If "pure" refers to something unmixed or unadulterated:
* Impure: This is the most direct opposite, meaning contaminated or mixed with other substances.
* Mixed: This implies that something is a combination of different elements.
* Adulterated: This refers to something that has been made impure by adding something inferior or harmful.
* Contaminated: This indicates that something has been made impure by the presence of harmful substances.
If "pure" refers to something morally good or innocent:
* Corrupt: This implies a loss of moral integrity or ethical standards.
* Wicked: This refers to something evil or morally wrong.
* Sinful: This implies a violation of moral or religious laws.
* Tainted: This suggests that something has been made impure or morally questionable.
If "pure" refers to something simple or basic:
* Complex: This indicates that something is intricate or made up of many parts.
* Elaborate: This refers to something that is highly detailed or complicated.
* Sophisticated: This implies that something is highly developed or complex.
* Artificial: This refers to something that is not natural or genuine.
If "pure" refers to something clear or bright:
* Cloudy: This implies that something is unclear or obscured.
* Dark: This refers to something that lacks brightness or light.
* Muddy: This suggests that something is unclear or indistinct.
* Opaque: This means that something is not transparent or translucent.
The best opposite for "pure" will depend on the specific context in which you are using the word.