n. A creature that is not (yet) at the level of understanding of a human being, such as a presymbolic child or an animal.
The Century Dictionary and Cyclopedia
Having attributes or qualities lower than the human in the scale of being: the opposite of superhuman.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. belonging to a group below humans in evolutionary development
Word Usage
"The task might also be called infrahuman, because the sort of omniscience which such complete historical science would achieve would merely furnish materials for intelligence: it would be inferior to intelligence itself."