Eucalyptus retinens is a tree that typically grows to a height of and forms a
lignotuber. The bark on the trunk and larger branches is rough, fibrous or flaky and grey and the bark on the thinner branches is grey to greenish. Young plants and
coppice regrowth have stems that are square in cross-section and
sessile leaves that are long, wide and arranged in opposite pairs with their bases surrounding the stem. Adult leaves are the same shade of glossy green on both sides, lance-shaped or curved, long and wide, tapering to a
petiole long. The flower buds are arranged in leaf
axils in groups of seven on an unbranched
peduncle long, the individual buds sessile or on
pedicels up to long. Mature buds are oval to oblong, long and wide with a rounded or conical
operculum. The flowers are white and the fruit is a woody, cup-shaped, cylindrical or hemispherical
capsule long and wide with the valves protruding above the rim of the fruit. ==Taxonomy and naming==