Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun placeholder

2 senses of placeholder

Sense 1
proxy, placeholder, procurator -- (a person authorized to act for another)
       => agent -- (a representative who acts on behalf of other persons or organizations)

Sense 2
placeholder -- (a symbol in a logical or mathematical expression that can be replaced by the name of any member of specified set)
       => variable -- (a symbol (like x or y) that is used in mathematical or logical expressions to represent a variable quantity)