The etymology of "solstice" was a puzzle to me. The "sol" part refers, of course, to the sun. No problem there. However, I had to look up the derivation of the "stice" part.
"Stice" comes from the Latin word for stopping or standing. Therefore, a solstice means a stopping of the Sun. In particular, the summer solstice marks the northernmost extreme that the Sun reaches in the sky before the Sun appears to stop and reverse its direction.
The "stice" part of the word seemed unfamiliar to me until I realized that the word "armistice" means the stoppage of arms or armed conflict during a war.