Translucent is to "Opaque" as "Porous" is to ___?

The answer to the question above is "compact" or "impermeable' based on the words relationship shown on the question above. The relationship between the words in the question shows the antonym relationship. The "opaque'' has the antonym relationship with the "translucent' word. Therefore, the antonym of the"porous" word is "compact" or "impermeable".