Definition of fallacious in English:

Share this entry


Pronunciation: /fəˈlāSHəs/


Based on a mistaken belief: fallacious arguments
More example sentences
  • Speculation that MMR could be replaced by a series of individual vaccines was based on fallacious reasoning and would return Britain to the ‘dark ages’, he said.
  • Both the settlers and the far left believed that the disengagement could not take place because each group was gripped by a fallacious belief system, in which contradiction or dissent was impossible.
  • As this magazine reluctantly pointed out at the time, it is based on a fallacious theory that the brain works in strict hierarchical order: that the midbrain develops before the cortex.
erroneous, false, untrue, wrong, incorrect, flawed, inaccurate, mistaken, misinformed, misguided;
specious, spurious, bogus, fictitious, fabricated, made up;
groundless, unfounded, ill-founded, unproven, unsupported, uncorroborated
informal phony, full of holes



Pronunciation: /fəˈlāSHəslē/
Example sentences
  • Kupchan utilises some inappropriate historical analogies such as fallaciously comparing the Eastern and Western Roman Empire schism, which was as much about religious power as anything, to the growing friction between the EU and USA.
  • He may start fallaciously believing that the Federal Reserve is not in fact part of the federal government, but is instead controlled by wealthy Zionists.
  • At the time one reasons fallaciously, one. typically does so unwittingly (One does not very often commit fallacies deliberately).


Pronunciation: /fəˈlāSHəsnəs/
Example sentences
  • I suppose it would be pointless to explicate the obvious fallaciousness of that "logic"; those who don't already see it probably don't want to.
  • But to submit moral and even political issues to a vote, at least to the logically minded, is to celebrate fallaciousness. Democratic rule is inherently irrational, built entirely on fallacy.


Early 16th century: from Old French fallacieux, from Latin fallaciosus, from fallacia (see fallacy).

Words that rhyme with fallacious

Athanasius, audacious, bodacious, cactaceous, capacious, carbonaceous, contumacious, Cretaceous, curvaceous, disputatious, edacious, efficacious, farinaceous, flirtatious, foliaceous, fugacious, gracious, hellacious, herbaceous, Ignatius, loquacious, mendacious, mordacious, ostentatious, perspicacious, pertinacious, pugnacious, rapacious, sagacious, salacious, saponaceous, sebaceous, sequacious, setaceous, spacious, tenacious, veracious, vexatious, vivacious, voracious

For editors and proofreaders

Syllabification: fal·la·cious

Share this entry

What do you find interesting about this word or phrase?

Comments that don't adhere to our Community Guidelines may be moderated or removed.