Rounded division or segment of a leaf or other organ. Technically the sinuses between the lobes should not be deeper than half way to the midrib (deeper sinuses would make it a parted leaf), but that distinction is not always used in common practice; A lobed leaf can be symmetrical or asymmetrical and vary in sizes depending on species.
Many of the Acer species, like the Hedge Maple shown here, have lobed leaves that provide distinctively identifiable characteristics in the field.
Small lobes around leaf edges, smaller than lobed. Lobed leaves (or petals, etc.) are divided to about the mid-point between the midrib and the margin. Lobulate leaves have less deeply divided sections, and are further described using another characteristic i.e. a serrated-lobulate margin.