Let’s look at the word PANDEMIC itself.

The suffix ‘-ic’ in English is an adjective suffix:

ANGELIC: having the qualities of an angel
CUBIC: having the characteristics of a cube
PROBLEMATIC: posing a problem https://www.merriam-webster.com/words-at-play/word-of-the-year/pandemic

Some such words we only know as nouns, but if you dig back far enough, their roots are adjectival:

MUSIC (originally) “of the muses”
MAGIC (originally) “of the magus (magician)”
LYRIC (originally) “of a lyre”
TOPIC (originally) “of a place (topos)”

The English ‘-ic’ corresponds to the French suffix ‘-ique’ and the Latin suffix ‘-icus.’

So, for example:

we have the English ‘scholastic’
from the French ‘scholastique’
from the Latin ‘scholasticus’

PANDEMIC is from the Greek word ‘pandēmos’ “of or belonging to all the people,” from ‘pan-‘ (“all”) + ‘dēmos’ (“populace”).

‘Dēmos’ is also the root of DEMOCRACY and DEMAGOGUE.

The original use of PANDEMIC in English in the 1600s was as an adjective meaning “widespread, universal.” It even had the meanings “vulgar, common” in our 1934 Unabridged edition.

This general meaning was then frequently medical, as in “pandemic disease” or “pandemic fever.”

By the 1800s, this use had become so widespread that PANDEMIC had become a noun that could stand on its own, meaning “a disease on all the people.” https://www.merriam-webster.com/words-at-play/epidemic-vs-pandemic-difference

Other words that use the Greek root ‘pan-‘ include:

PANACEA (originally) “remedy for all”
PANDEMONIUM (originally) “all the demons”
PANTHEON (originally) “all the gods”
PANORAMA (originally) “ability to see all”

Of course, some of these ‘-ic’ words are used commonly as both adjectives and nouns:

ACADEMIC
ALCOHOLIC
ARCTIC
DIABETIC
ELASTIC
EPIC
MYSTIC
TONIC