The word 'solstice' comes from Latin meaning 'sun' and what verb?

The word “solstice” comes from Latin for “sun” and “to stand still.”

It derives from Latin sol, meaning “sun,” and sistere, meaning “to stand still” or “to cause to stand.” The combined Latin term solstitium described the point at which the Sun’s apparent seasonal movement pauses before reversing direction.

The Sun does not literally stop moving. Earth continues rotating, so the Sun still appears to travel across the sky each day. What briefly reaches a turning point is the Sun’s apparent north–south position: around the June solstice it stops moving northward and begins drifting southward, while around the December solstice it reverses the other way.

This etymology explains a common misconception. A solstice is not simply the hottest or coldest day, and “stand still” refers to apparent solar motion, not a halt in the Sun’s daily journey. English also has older, now uncommon calques such as “sunstead” and “sunstay.”