noun
bungler; clumsy person; all thumbs
Refers to a person who is habitually clumsy, awkward, or inept, especially with manual tasks. Often used self-deprecatingly or as mild criticism.
私は不器用者で、料理がうまくできない。
I'm a clumsy person and can't cook well.
彼は不器用者だから、細かい作業は任せられない。
He's all thumbs, so we can't entrust him with delicate work.
Compound of 不器用 (bukiyō, 'clumsy') + 者 (mono, 'person'). The exact historical derivation is uncertain, but the spelling is conventionally associated with the meaning.