excellent: [14] The underlying notion of excellent is of physically ‘rising above’ others. It comes via Old French from the present participle of Latin excellere. This was a compound verb formed from the prefix ex- ‘out’ and a hypothetical verbal element *cellere, which evidently meant something like ‘rise, be high’: it derived ultimately from an Indo-European base *kol-, *kel- which also produced English column, culminate, and hill.
There is little evidence of its literal use in Latin; the metaphorical ‘be outstanding’ evidently elbowed it aside at an early stage. (English acquired excel itself in the 15th century, incidentally.) => column, culminate, hill
mid-14c., from Old French excellent "outstanding, excellent," from Latin excellentem (nominative excellens) "towering, prominent, distinguished, superior, surpassing," present participle of excellere "surpass, be superior; to rise, be eminent" (see excel). Related: Excellently.