spurious

Concise Oxford English Dictionary © 2008 Oxford University Press:
spurious /ˈspjʊərɪəs/

▶adjective

• 1 false or fake.

• 2 (of a line of reasoning) apparently but not actually valid.

• 3 archaic (of offspring) illegitimate.

– derivatives
spuriously adverb,
spuriousness noun.

– origin C16: from L. spurius ‘false’ + -ous.