Each country in the European Union has its own definition of a forest and the European Commission has defined forestland as having at least 20% canopy closure (10% in the Mediterranean forests) and a minimum area of 0.5 ha. (1 ha. = 0.01 kmÂ²). Elsewhere, the definition of a tree can vary.
Lunula: the crescent-shaped area at the base of the human fingernail.
Cannula: A hollow tube with a sharp, retractable inner core that can be inserted into a vein, an artery, or another body cavity.