If you hear someone use the letters “CD,” they are abbreviating the term “certificate of deposit.” And according to Investopedia, a CD is A savings certificate entitling the bearer to receive interest.
A CD bears a maturity date, a specified fixed interest rate and can be issued in any denomination.
CDs are generally issued by commercial banks and are insured by the FDIC. The term of a CD generally ranges from one month to five years.
It can get a bit confusing, but for a more clear explanation with examples, click on the video and listen to Scott Halliwell from USAA.