PIE base ‘to observe’. See also *weid- ‘to see’, root of vision, and wer-³ ‘to perceive, watch out for’, root of theory.
Derivatives include spectacle, speculate, aspect, auspicious, especial, espy, spy, suspect, respect, introspect, despicable, suspicion, and telescope.
[Pokorny spek̂- ‘to watch’, p. 984.]