size specifier
The word such as dword ptr that tells an x86-64 assembler how many bytes a memory operand covers when no register says so.
In Intel syntax, byte ptr, word ptr, dword ptr and qword ptr fix the operand size of a memory operand (1, 2, 4, 8 bytes) when no register operand implies it; AT&T syntax uses the b, w, l, q mnemonic suffixes instead.
See also