regarding
[preposition]
Synonyms: concerning, about, as regards, in or with regard to, on the subject of, re, respecting, with reference to

[TahlilGaran] English Synonym Dictionary ▲

re‧gard‧ing /rɪˈɡɑːdɪŋ $ -ɑːr-/ preposition formal
a word used especially in letters or speeches to introduce the subject you are writing or talking about Synonym : concerning, with regard to:
Regarding your recent inquiry, I have enclosed a copy of our new brochure.

[TahlilGaran] Dictionary of Contemporary English ▲

regarding
preposition
BAD: Regarding to your letter of 22 November, I have referred your query to our accounts department.
GOOD: Regarding your letter of 22 November, I have referred your query to our accounts department.

Usage Note:
regarding (WITHOUT to ): 'If you have any questions regarding any of our services, please feel free to contact me.'
See also REFERENCE (reference), REGARD 1 (regard)

[TahlilGaran] Dictionary of Common Errors ▲