All 4 Uses

monologue
in
Sophie's Choice
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But I thought this might provoke Nathan into thinking I was pulling his leg; he might then embark again upon his monologue, which was becoming a trifle exhausting, so I merely smiled thinly, wrapping myself in an enigma, and replied, "I have a private source of income."†
p. 81.8 *

monologue = a long uninterrupted speech
On and on the voice went, a gentle monologue, lulling, soothing, murmurously infusing her with a sense of repose; it was a soft refrain so sedative indeed that soon she was no longer even embarrassed that the hands of this stranger were greenly stained with her own sour juices, and somehow she regretted that the one thought she had expressed to him, when she had first opened her eyes, had been the impossibly foolish Oh, I think I'm going to die.†
p. 113.9
She giggled at Nathan, carrying on a zany monologue in counterpoint to the depressing biography.†
p. 348.9
Gazing out at the grime-encrusted façade of the Wheatena factory—hulking, homely, its blue industrial windows reflecting the morning light—I shivered with happiness and again with pride at the sheer quality of what I had put into my book by dint of so much solitary work and perspiration and, yes, even occasional freshets of grief; and thinking once more of the as yet unwritten climax, I allowed myself to fantasize a line from the review of a dazzled critic of 1949 or 1950: "The most powerful passage of female interior monologue since Molly Bloom's."†
p. 491.1

Definitions:

(1) (monologue)
a long speech by one person, whether it's a dramatic speech in a play, a run-on talk that keeps others from getting a word in, or a comedian's continuous stream of jokes and stories delivered alone

Although less frequently used, "monolog" is also a correct spelling in the United States.
(2) (meaning too rare to warrant focus)