This is the 2269th most frequent Japanese word.
透明
Transparent.
In this sentence, '透明' is used as an adjective to describe the quality of water being clear or see-through.
水は透明で、底が見えます。
The water is transparent, and the bottom is visible.
Here, '透明' metaphorically describes the clarity or obviousness of someone's intentions, applying the concept of transparency to abstract ideas.
彼の意図は透明だった。
His intentions were clear.
In this context, '透明' is an adjective describing the glass material, emphasizing its ability to allow light and visibility through.