The word 癌症 (áizhèng) for "cancer" is formed by combining two meaningful characters into a single concept. The first character, 癌 (ái), is itself a constructed character pictorially representing the disease: its top part is the "sickness" radical (疒), indicating illness, while the bottom part, 嵒 (yán, meaning "cliff" or "crag"), was chosen phonetically but also evokes the hard, rock-like tumors characteristic of the disease. This character 癌 is then combined with the second character, 症 (zhèng), which means "disease" or "condition", to specify and generalize it as the category of illness. Thus, the term literally and metaphorically conveys "the rock-like growth disease".