SWaP is an Acronym commonly used in the security/aerospace industries. It stands for Size Weight and Power.
It refers to the Size, Weight and Power Consumption requirements of specific components in full systems or for the whole system itself..
It’s a commonly used acronym in both industries (mentioned abode) due to them usually having high requirements for space taken, power use and weight limit of certain components.
Lower SWaP components are necessary for highly efficient systems.