Definitions of burnt:

• adjective:   treated by heating to a high temperature but below the melting or fusing point

  Example: "Burnt sienna"

• adjective:   having undergone oxidation
• adjective:   ruined by overcooking

  Example: "She served us underdone bacon and burnt buscuits"

• adjective:   destroyed or badly damaged by fire

  Example: "A charred bit of burnt wood"

• adjective:   hardened by subjecting to intense heat