This page deals with slang terms for a Zombie apocalypse, in the heat of the moment it's easy to garble in horror at the situation and important messages are lost so easy terms are introduced by the military which are inevitably adopted and mutated by civilians.
In art, an underpainting is an initial layer of paint applied to a ground, which serves as a base for subsequent layers of paint. Underpaintings are often monochromatic and help to define colour values for later painting.
Full Definition of UNDERTOW. 1. : the current beneath the surface that sets seaward or along the beach when waves are breaking upon the shore.2. : an underlying current, force, or tendency that is in opposition to what is apparent. See undertow defined for English-language learners. a current beneath the surface of the water that moves away from or along the shore while the surface water above it moves toward the shore. Spanish Central: Spanish translation of undertow.