1 a : fraudulently substituted : spurious
b : of a child (1) : falsely presented as a genuine heir (2) : illegitimate
2 a : imaginary
b : of the nature of or based on a supposition : hypothetical
Did You Know?
The Latin verb "supponere," meaning "substitute," has several legitimate heirs in English, including "supposititious" (which dates from the early 17th century) and "supposition" (a 15th century addition). The "fraudulent" and "illegitimate" meanings of "supposititious" trace back to "supponere" in a fairly direct route, whereas the "imaginary" and "hypothetical" meanings were influenced by the meanings of "supposition." In legal contexts, "supposititious" is primarily used in its earlier senses, as in "a supposititious (fraudulent) will" or "the child was supposititious (illegitimate)." When something hypothetical is being considered, the adjective "suppositious" is often preferred over "supposititious."
"I sat looking at Peggotty for some time, in a reverie on this supposititious case: whether, if she were employed to lose me like the boy in the fairy tale, I should be able to track my way home again by the buttons she would shed." -- From Charles Dickens' 1850 novel David Copperfield
"If I had Clark for a son, I would probably take my supposititious heir to lunch myself." -- From Tim Sandlin's 2010 novel Social Blunders
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Word Family Quiz
What relative of "supposititious" can mean "to take something to be true "? The answer is ...
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