* 不器用 (bukiyou): This is a common and versatile word meaning "inept," "awkward," or "clumsy." It refers to a lack of skill or dexterity in general, not just physical clumsiness. This is probably the closest overall translation.
* ぎこちない (gikochi nai): This means "awkward" or "stiff." It describes someone who moves in a clumsy and unnatural way.
* ドジ (doji): This word specifically refers to someone who is accident-prone and makes a lot of clumsy mistakes. It carries a more playful or humorous connotation than "bukiyou."
* 下手 (heta): This means "unskilled" or "poor at." While not directly translating to "clumsy," it can be used to describe someone clumsy at a specific task, like "料理が下手 (ryōri ga heta)" meaning "bad at cooking" implying clumsiness in the kitchen.
The best choice depends on the context. For general clumsiness, 不器用 (bukiyou) is a safe bet. If you want to emphasize the accident-prone nature, use ドジ (doji). If the clumsiness is more about awkward movements, use ぎこちない (gikochi nai).