Ineffable is an adjective that deals with ideas that shouldn’t be expressed. This includes uttering the name of gods such as the name of God in Judaism (YHWH) and arch-villains like Lord Voldemort of the Harry Potter series and also extends to principles, arguments and terminology that are plain senseless and illogical.
The word carries a mystical and theological connotation and seems to be a favorite among poets and literati. Here are some examples of the way the word has been used in literature:
“God does not play dice with the universe; He plays an ineffable game of His own devising, which might be compared, from the perspective of any of the other players [i.e. everybody], to being involved in an obscure and complex variant of poker in a pitch-dark room, with blank cards, for infinite stakes, with a Dealer who won’t tell you the rules, and who smiles all the time.”
— Terry Pratchett (Good Omens: The Nice and Accurate Prophecies of Agnes Nutter, Witch)
“You have to be an artist and a madman, a creature of infinite melancholy, with a bubble of hot poison in your loins and a super-voluptuous flame permanently aglow in your subtle spine (oh, how you have to cringe and hide!), in order to discern at once, by ineffable signs―the slightly feline outline of a cheekbone, the slenderness of a downy limbs, and other indices which despair and shame and tears of tenderness forbid me to tabulate―the little deadly demon among the wholesome children; she stands unrecognized by them and unconscious herself of her fantastic power.”
— Vladimir Nabokov (Lolita)
“Both light and shadow are the dance of Love.
Love has no cause, it is the astrolabe of God’s secrets.
Lover and loving are inseparable and timeless.
Although I may try to describe love,
when I experience it, I am speechless.
Although I may try to write about love, I am rendered helpless.
My pen breaks, and the paper slips away
at the ineffable place where lover loving and loved are one.
Every moment is made glorious by the light of Love.”
— Rumi