From uproar + -ious (a variant of -ous).

• (RP) IPA: /ʌpˈɹɔː.ɹɪ.əs/
• (America) IPA: /ˌʌpˈɹɔ.ɹi.əs/

uproarious

1. Causing, or likely to cause, an uproar.
2. Characterized by uproar, that is, loud, confused noise, or by noisy and uncontrollable laughter.

   Synonyms: uproarish, Thesaurus:noisy

   • 1843 December 18, Charles Dickens, “Stave Two. The First of the Three Spirits.”, in A Christmas Carol. In Prose. Being a Ghost Story of Christmas, London: Chapman & Hall, […], →OCLC ↗, pages 68–69 ↗:

     The noise in this room was perfectly tumultuous, […] every child was conducting itself like forty. The consequences were uproarious beyond belief; but no one seemed to care; on the contrary, the mother and daughter laughed heartily, and enjoyed it very much; and the latter, soon beginning to mingle in the sports, got pillaged by the young brigands most ruthlessly.

   • 1853, Solomon Northup, chapter XV, in [David Wilson], editor, Twelve Years a Slave. […], London: Sampson Low, Son & Co.; Auburn, N.Y.: Derby and Miller, →OCLC ↗, page 219 ↗:

     One "set" off, another takes its place, he or she remaining longest on the floor receiving the most uproarious commendation, and so the dancing continues until broad daylight. It does not cease with the sound of the fiddle, but in that case they set up a music peculiar to themselves.

   • 1921, L[yman] Frank Baum [actually Ruth Plumly Thompson], “Dorothy and Sir Hokus Come to Fix City”, in The Royal Book of Oz […], Chicago, Ill.: The Reilly & Lee Co., →OCLC ↗, page 165 ↗:

     The two bushes looked up in surprise, and when they saw Dorothy, the Cowardly Lion and Sir Hokus, they fell into each other's branches and burst into the most uproarious laughter.

   • 1922 August, Baroness Orczy [i.e., Emma Orczy], “One Crowded Hour of Glorious Life”, in The Triumph of the Scarlet Pimpernel, 1st American edition, New York, N.Y.: George H[enry] Doran Company, →OCLC ↗, § 1, page 62 ↗:

     At the uproarious cheering which greeted his appearance, [Maximilien] Robespierre advanced into the open, whilst a sudden swift light of triumph darted from his narrow, pale eyes.

3. (by extension) Extremely funny; hilarious.

   Synonyms: Thesaurus:funny

4. (figuratively) In a mess; dishevelled, untidy.

• uproar
• uproarish
• uproarishly
• uproarishness

• French: tumultueux