noun, noun which may take the genitive case particle 'no'
with all one's might; with one's whole body and soul
Used to describe putting all of one's physical or mental energy into an action. Often appears as 渾身の〜 (e.g., 渾身の力, 渾身の一撃).
彼は渾身の力を込めて岩を押した。
He pushed the rock with all his might.
これは作家が渾身の思いを込めて書いた作品だ
This is a work the author poured his heart and soul into.
全力 is a more common and neutral word for 'full power' or 'all one's strength', while 渾身 emphasizes a more dramatic, whole-body effort, often used in literary or emphatic contexts.
From 渾 (all, whole) and 身 (body). The exact historical derivation is uncertain, but the compound literally means 'whole body' and is used figuratively for total effort.