thumbnail toolbar (n)~ A toolbar control that is embedded in a window’s thumbnail preview. Thumbnail toolbars are a feature of pinned sites in Internet Explorer 9. thumbprint (n)~ A hexadecimal string that contains the SHA-1 hash of the certificate. thunk (n)~ A small section of code that performs a translation or conversion during a call or indirection. For example a thunk is used to change the size or type of function parameters when calling between 16-bit and 32-bit code.