"Illustrious" also means "widely known and esteemed"--this applies to the Sun God Phoebus, but the chosen definition fits the example sentence better because it describes the glory or "brilliant radiant beauty" that is emphasized by the "dazzling light" that hurts Phaeton's sight.
'Till pressing forward through the bright abode,
He saw at distance the illustrious God:
He saw at distance, or the dazling light
Had flash'd too strongly on his aching sight.
"Verdure" means the green, lush, growing nature of leaves or other vegetation, and indicates a healthy condition or state. In the example sentence, the verdant leaves contrast with red blood, both of which come from Phaeton's sisters, who have turned into trees from their grief.
She tears the bark that to each body cleaves,
And from their verdant fingers strips the leaves:
The blood came trickling, where she tore away
The leaves and bark: the maids were heard to say,
"Forbear, mistaken parent, oh! forbear;
A wounded daughter in each tree you tear;
of imposing height; especially standing out above others
"Lofty" also means "having or displaying great dignity or nobility" and "of high moral or intellectual value"--although the example sentence is focused on the physical height of the city that the God (Mercury) is flying over, all three definitions would be fitting for Athens.
This done, the God flew up on high, and pass'd
O'er lofty Athens, by Minerva grac'd,
And wide Munichia, whilst his eyes survey
All the vast region that beneath him lay.
characterized by pomp and ceremony and stately display
Remember that the melody "Pomp and Circumstance" plays when graduates enter the graduation ceremony. While graduates might connect to the other definition of "pompous" ("puffed up with vanity"), the maids in the bright procession would not, because they are returning from paying homage to the goddess Minerva and are described as "solemn" ("dignified and somber in manner or character").
The God well pleas'd beheld the pompous show,
And saw the bright procession pass below;
(used in combination) affected by something overwhelming
"Smitten" is the past participle of "smite" which means "inflict a heavy blow on, with the hand, a tool, or a weapon" and "affect suddenly with deep feeling"--both definitions fit, because Aglauros was stroked by the hands of Envy and stung with prickly thorns. This causes her to hate the god who, smitten with her sister, asked for her help. She is compared to ice that is smitten by the sun, but instead of melting, she is transformed into marble when she breaks her promise to the god.
Full of the dream, Aglauros pin'd away
In tears all night, in darkness all the day;
Consum'd like ice, that just begins to run,
When feebly smitten by the distant sun;
"Sublime" also means "worthy of adoration or reverence" and "inspiring awe" and "of high moral or intellectual value"--while the example sentence focuses on Mercury flying up into the sky to enter Olympus, these three definitions could also describe the home of the Gods.
Jove saw him enter the sublime abodes,
And, as he mix'd among the crowd of Gods,
Beckon'd him out, and drew him from the rest,
And in soft whispers thus his will exprest.