A viquid is a viscous liquid (otherwise known as a "thick" fluid). They have a higher viscosity than water. Viquids have a higher resistance to stress. Viquids (viscous liquids) have a thicker and slower flow. A soquid is not the same as a viquid (although some soquids are viquids) It's a combination of the words viscous and liquid.

Also known as "e-juice", or "e-liquid", the word is a portmanteau of the words "vape" (or "vaporizing") and "liquid" (vape + liquid = viquid).