transparent, permeate, filter, penetrate
透 centers on the idea of passing through a barrier or medium: light passing through something transparent, liquid permeating a material, or filtering out impurities. The core is movement across or into a substance.
透 combines 辶 (movement) with 秀, which likely contributes the sound and the idea of something emerging or passing through. The exact historical development of 秀 within this character is uncertain.
The movement radical 辶 wraps around 秀, like something traveling through a passage. Imagine light moving through a clear window: it permeates and makes things visible.
For トウ, picture a transparent toe sock that lets your toes show through: toe -> トウ, and the fabric is so thin it's almost transparent.
transparent; clear
to be transparent; to show through
permeation (of thought, ideology, culture, etc.); infiltration (e.g. of ideas); spread; penetration (e.g. into a market); pervasion
penetration; permeation; transmission
seeing through
opaque; obscure; murky; turbid
dialysis
see-through; sheer
watermark (in a stamp, banknote, etc.)
to be transparent; to be see-through; to be clear
under-shoulder swing-down; technique of grasping the arm of the opponent, the moment he comes forward, while stepping out of line and pushing down on the shoulder blade with the other hand, thus pulling him down
permeation (e.g. of water); percolation; seepage
open; frank; outspoken; unreserved; straightforward; honest
code-transparent data communication
data circuit transparency
opacity
opacity
sense of uncertainty; lack of clarity; indecisiveness
gouache
(artificial) dialysis