panegyric (n.)

1590s, "open assembly place, chief public square and marketplace of a town; popular political assembly held in such a place," from Greek agora "an assembly of the People" (as opposed to a council of Chiefs); "the place of assembly; a marketplace" (the typical spot for such an assembly), from ageirein "to assemble" (from PIE root *ger- "to gather").

The Greek word also could mean "public speaking," and "things to be sold." For sense, compare Roman forum.

word-forming element meaning "all, every, whole, all-inclusive," from Greek pan-, combining form of pas (neuter pan, masculine and neuter genitive pantos) "all," from PIE *pant- "all" (with derivatives found only in Greek and Tocharian).

Commonly used as a prefix in Greek (before a labial pam-; before a guttural pag-), in modern times often with nationality names, the first example of which seems to have been Panslavism (1846). Also panislamic (1881), pan-American (1889), pan-German (1892), pan-African (1900), pan-European (1901), pan-Arabism (1930).

Proto-Indo-European root meaning "to gather." 

It forms all or part of: aggregate; aggregation; agora; agoraphobia; allegory; category; congregate; cram; egregious; gregarious; panegyric; paregoric; segregate.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit gramah "heap, troop;" Greek ageirein "to assemble," agora "assembly;" Latin grex "flock, herd," gremium "bosom, lap;" Old Church Slavonic grusti "handful," gramota "heap;" Lithuanian gurgulys "chaos, confusion," gurguolė "crowd, mass;" Old English crammian "press something into something else."