adjective
alkaline
AL-kuhl-yn
adjective
1
Having the chemical properties of an alkali; basic rather than acidic.
"Soap is alkaline, which is why it can feel slippery on the skin."
"The soil here is quite alkaline, so acid-loving plants struggle."
2
Having a pH greater than 7 on the standard scale.
"The test strip turned blue, showing the water was alkaline."
"A pH of 9 is mildly alkaline."
How to Use Alkaline
Learner’s notesIn plain EnglishChemically basic — the opposite of acidic — as measured by a pH above 7.
Easily confused with
Common pairings
alkaline soil
alkaline solution
alkaline battery
Word Forms
more alkaline comparative, alkalines plural, most alkaline superlative
Study it as flashcards or scroll it in Flow — saved to your collection.
Test yourself on “alkaline”
A quick quiz — meaning, synonyms & usage
→
Fill the Gap
Can you complete this real example?
Soap is _____, which is why it can feel slippery on the skin.
Etymology
From "alkali," which came into English via Arabic al-qily, the ashes of a salt-tolerant desert plant once burned to make soap and glass.