(of a substance) capable of being dissolved in some solvent (usually water)
"The sugar cubes are highly soluble, so they vanished instantly when dropped into the hot tea."
Able to be dissolved.
"The sugar cubes were soluble in hot tea, disappearing completely within moments."
Soluble comes from the Latin word solvere, meaning "to loosen," which entered Middle English via Old French. The term originally described something that could be loosened or dissolved, eventually becoming our modern word for substances that can dissolve in a liquid.