Being at neither one extreme nor the other; intermediate. Intervening between an earlier and a later period of time; being an intermediate part of a sequence or series: the middle years. Geology Of or relating to a division of geologic time between an earlier and a later division: the Middle Paleozoic. Equally distant from extremes or limits; central: the middle point on a line. Of or relating to a stage in the development of a language or literature between earlier and later stages: Middle Swedish. Grammar Of, relating to, or being a verb form or voice in which the subject both performs and is affected by the action specified. An area or a point equidistant between extremes; a center: the middle of a circle. Something intermediate between extremes; a mean. The interior portion: the middle of a chain. The middle part of the human body; the waist. Logic A middle term. Grammar The middle voice. Grammar A verb form in the middle voice. To place in the middle. Nautical To fold in the middle: middle the sail.