Puttable Bonds

Also known as Put Bond, Retractable Bond
Puttable Bonds - The investor can sell the bond back to the issuerr at a stated earlier date. The issuer is compensated by a lower coupon

Put options give the bondholder the right to sell the bond back to the issuer at the "put price" on specified days

Put provisions depend on the indenture (the legal binding document which sets out the terms and conditions)

Yield to Put

This is similar to Yield to Call although a lot less common.

Yield to Worst

This is just the lower of the Yield to maturity and the Yield to Call.
This is often quoted as the lowest yield out of the YTM and YTC or YTP
Often abbreviated to YTW.