The bronze script of character Temple is
Which means "Right here", "From here", "Here is our base".
Some people think that it is character Stop or Foot - 止 (Post 93).
Which implies that Solid (can't be moved), Stable, etc.
The two meanings are close. But it likes more like character Of - 之. The top should be mainstay, either the physical buildings or government power, or laws. It is impossible for people to move it by hands. However, if you think that it is the character Stop, which makes sense too.
The character originally means the buildings of Dynasty (government), when Buddhism was introduced into China, it is said that the buddha was originally settled in this kind buildings, or similar buildings. Gradually its meaning changed to Temple, the meanings of government building or power or laws disappeared because the temples moved out of the government buildings.
The big seal script of the character is
Same as clerical script.
The pinyin of 寺 is Si4.
Right now, 寺 is most of time specifically for Buddhist temple unless there is explanation otherwise. Most of other temples (if not all) are called 庙 (Post 318). People normally use "寺庙“ (Put the two characters together) to mean all religious temples.