noun-modifying (irregular)
perfectly clear; crystal clear; limpid
Describes something completely clear and transparent, often used for water, air, sky, or sounds. Also used figuratively for a pure, unclouded state of mind or feeling.
澄み切った青空が広がっている。
A perfectly clear blue sky stretches out.
湖の水は澄み切っていて、底まで見える。
The lake water is crystal clear, and you can see all the way to the bottom.
彼女の澄み切った声が会場に響いた。
Her clear, pure voice resonated through the hall.
Base verb meaning 'to become clear'; 澄み切った is the past attributive form of 澄み切る, which adds the nuance of 'completely' or 'thoroughly'.
Also means 'to be transparent/clear', but focuses more on physical transparency; 澄み切った often implies purity and lack of cloudiness in a broader sense.
Compound of 澄み (continuative form of 澄む 'to become clear') + 切る (here as an auxiliary verb meaning 'to do completely').