The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
spek-
DEFINITION:
To observe. Oldest form *spe-, becoming *spek- in centum languages. Derivatives include espionage, spectrum, despise, suspect, despicable, bishop, and telescope. I. Basic form *spek-.1a.espy, spy, from Old French espier, to watch; b.espionage, from Old Italian spione, spy, from Germanic derivative *speh-n-, watcher. Both a and b from Germanic *spehn.2. Suffixed form *spek-yo-.specimen, spectacle, spectrum, speculate, speculum, spice; aspect, circumspect, conspicuous, despise, expect, frontispiece, inspect, introspect, perspective, perspicacious, prospect, respect, respite, retrospect, spiegeleisen, suspect, transpicuous, from Latin specere, to look at. 3. species, specious; especial, from Latin specis, a seeing, sight, form. 4. Suffixed form *spek-s, “he who sees,” in Latin compounds. a. Latin haruspex (see gher-); b. Latin auspex (see awi-). 5. Suffixed form *spek--.despicable, from Latin (denominative) dspicr, to despise, look down on (d-, down; see de-). 6. Suffixed metathetical form *skep-yo-.skeptic, from Greek skeptesthai, to examine, consider. II. Extended o-grade form *spoko-.scope, –scope, –scopy; bishop, episcopal, horoscope, telescope, from metathesized Greek skopos, one who watches, also object of attention, goal, and its denominative skopein (< *skop-eyo-), to see. (Pokorny spe- 984.)
-, becoming *spek- in centum languages. 
n-, watcher. Both a and b from Germanic *speh
s, a seeing, sight, form. 4. Suffixed form *spek-s, “he who sees,” in Latin compounds. a. Latin haruspex (see gher
-); b. Latin auspex (see awi-). 5. Suffixed form *spek-
-. despicable, from Latin (denominative) d
, to despise, look down on (d
