Ridiculous means so silly or unreasonable that it invites laughter. A ridiculous hat, a ridiculous suggestion, this is ridiculous.
It is used far more in exasperation than in amusement — this is ridiculous is what people say in a queue that has not moved. Applied to prices and quantities it works as a plain intensifier: a ridiculous amount of food, ridiculously cheap. The adverb ridiculously is extremely common in that role. Note the spelling, which is the trap: ridiculous has an i in the middle where ridicule has one too, and the common misspelling redic- comes straight from how it is said.
1adjectiveridiculousSo silly or unreasonable that it deserves to be laughed at.
“The whole plan was ridiculous from the start.”
synonyms: absurd, preposterous, laughable
2adjectiveintensifyUsed to intensify, meaning extreme.
“They put a ridiculous amount of salt in it.”
Too few real examples of this word to estimate which sense is commonest.
ridiculous is a degree of absurdity.
Also accepted in games: absurd
Latin ridiculus meant laughable, from ridere, to laugh — the same verb behind deride and risible. The word has never meant anything but worthy of being laughed at, though English now uses it far more often about things than about people.
Latin
rīdiculus — laughable, ridiculous
English, today
ridiculous
Latin rīdiculus (“laughable, ridiculous”); Equivalent to ridicule + -ous.
Etymology from Wiktionary, CC BY-SA