An instrument for observing distant objects.
A watcher from afar.
combined
Greek
tēleskopos
‘far-seeing’
into New Latin
New Latin
telescopium
into English
English
telescope
‘optical instrument by means of which distant objects appear nearer and larger’
Telescope came through scientific Latin telescopium from Greek material about seeing far away. Its name describes the job of the instrument without specifying a lens, a mirror, or even the sky.
This view explains the components. They are pieces of one construction, not consecutive borrowing stages.
The tele- in telephone carries the same idea of distance.