Internal/ɪnˈtɜːrnl/ Definition 1 of 4Pro Tip 1/3Beyond Sight Refers to what can't be seen directly, like thoughts or feelings hidden inside. She kept her internal disappointment hidden with a smile. Pro Tip 2/3Not External Opposite of 'external', which is visible or exists outside. His calm appearance belied the internal chaos he felt. Pro Tip 3/3Physical Space Describes the space within objects, like buildings or bodies. The internal structure of the building was complex.