uncountable nouns used as countable nouns (understanding - a understanding of...)

[Duc]

As far as I know,''understanding'' is uncountable but as i looked up in the dictionary ,i saw this: ''He has A good understanding of mathematics''
Please explain it for me
Thanks in advance
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[Alan]

Hi Duc,

This word 'understanding' doesn't fit easily into either the countable or uncountable category. All you can say about it is that it is usually used only in the singular. Its meaning is 'comprehension', which is also used primarily in the singular. Such nouns usually refer to concepts, substances or qualities that don't have defined limits. Words like: education, information, honesty, butter and so on.

Alan
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English as a Second Language
You can read my ESL story Phrasal Verbs/bring