All 6 Uses of

invoke
in
The Iliad by Homer - (translated by: Pope)

So Mars armipotent invades the plain, (The wide destroyer of the race of man,) Terror, his best-beloved son, attends his course, Arm'd with stern boldness, and enormous force; The pride of haughty warriors to confound, And lay the strength of tyrants on the ground: From Thrace they fly, call'd to the dire alarms Of warring Phlegyans, and Ephyrian arms; Invoked by both, relentless they dispose, To these glad conquest, murderous rout to those.†
Book 13 *

invoked = called upon

(235) "Swear then (he said) by those tremendous floods That roar through hell, and bind the invoking gods: Let the great parent earth one hand sustain, And stretch the other o'er the sacred main: Call the black Titans, that with Chronos dwell, To hear and witness from the depths of hell; That she, my loved-one, shall be ever mine, The youngest Grace, Pasithae the divine.†
Book 14

invoking = calling upon

The queen assents, and from the infernal bowers Invokes the sable subtartarean powers, And those who rule the inviolable floods, Whom mortals name the dread Titanian gods.†
Book 14

invokes = calls upon

Nor yet the pile, where dead Patroclus lies, Smokes, nor as yet the sullen flames arise; But, fast beside, Achilles stood in prayer, Invoked the gods whose spirit moves the air, And victims promised, and libations cast, To gentle Zephyr and the Boreal blast: He call'd the aerial powers, along the skies To breathe, and whisper to the fires to rise.†
Book 23

invoked = called upon

Definition:

to call upon

The exact meaning of invoke can depend upon its context. For example:

"invoking God's help"; or "invoking the spirit of the dead" -- to call upon a great or magical power
"I invoke the First Amendment"; or "I invoke the words of Thomas Jefferson" -- to cite or call upon for validation
"She invoked his sympathy and family memories." -- to call upon someone's feelings or memories
"She invoked his assistance." -- to call earnestly for
"The program invokes the subroutine" -- to call up a computer program