Concentration of solutes in the cell is less than solutes in the surrounding fluid, the fluid outside the cell is said to be

Hypertonic

Explanation:

There is a greater concentration of solutes outside the cell compared to inside the cell. This means the surrounding fluid is hypertonic to the solution inside the cell.

If the opposite were true, and there was a greater concentration of solutes inside the cell than outside, the outside solution would be hypotonic to the solution inside the cell.

If the concentration of solutes were the same inside and outside, the two solutions would be isotonic.

A good way to remember this is thinking about the term "hyper" - it is a prefix that means, "high". You find it in words like hyperactive and hyperventilate. If you remember that, then you will remember that a hypertonic solution has a higher concentration of solutes.