concern
n. C / Un. a feeling of worry about a situation, or something that is important to you. You use it when you care about a problem and want to fix it.
n. a state of anxiety or worry regarding a specific matter; alternatively, a matter of interest or importance to someone. Often used to describe a subject of professional or personal responsibility.
The teacher expressed concern about the student's grades.
The main concern for the engineering team is ensuring the bridge can withstand high winds during the winter.
While the immediate financial results were positive, the board expressed deep concern regarding the long-term sustainability of the current supply chain model in a volatile market.
Borrowed from Middle French concerner, from Medieval Latin concernō, concernere (“I distinguish, have respect to”), from Latin concernō (“to mix, sift, or mingle together, as in a sieve”), combined form of con- + cernō (“distinguish”).
Often followed by the prepositions 'about', 'for', or 'over'. When used to mean 'a business', it is always countable.
I have a concern about of the projectI have a concern about the projectLearners sometimes add an extra 'of' after 'about' when expressing worry, but 'concern about' should be followed directly by the noun phrase.