Since lost and loss are easily confused words and you might assume they are the same on accident, although they aren’t quite homophones. They both refer to the action of losing something; however, they come from different parts of speech in the common English language and have slightly different meanings.
The English word loss is a noun and is used to refer to the action of losing something or someone.
Lost is the past tense of lose or the past participle of lose.
Example sentences:
I took a terrible loss this year in the stock market due to the economic crisis. – Correct
I took a terrible lost this year in the stock market due to the economic crisis. – Incorrect
I lost my car keys somewhere between my car and the door in the garage. – Correct
I loss my car keys somewhere between my car and the door in the garage. – Incorrect