a usually tubular optical instrument for viewing distant objects by means of the refraction of light rays through a lens or the reflection of light rays by a concave mirror. any of various tubular magnifying optical instruments. RADIO TELESCOPE. to become forced together lengthwise with one part entering another as the result of collision. to slide or pass one within another like the cylindrical sections of a collapsible hand telescope. to become compressed or condensed. to cause to telescope. COMPRESS, CONDENSE.