Soonest

The earliest next opportunity. Grammatically superlative variation of the word soon.

(E.g. as a conclusion to an email) Charles will get back to you soonest.

by rakibo February 27, 2020

soonest

As quickly as is reasonable.

(Business letter): "I will look into the issue and get back to you soonest."

by Bilham March 11, 2014