invious

in•vi•ous (IN-vi-uhs)  adj

Definition:
untrodden, impassable, inaccessible, without paths or roads

inviousness noun

Related:
Synonyms: untrodden, impassable, inaccessible
Related Words: bivious, obvious, impervious, devious, deviate, previous

Sentence Examples:
• Of the very early history of Hastings we know practically nothing, save that it seems to have been for many years a place apart.  Shut off from the west by the invious flats of Pevensey, then one vast network of lagoons: from the east by the greater marsh of Romney; secluded on the north by the grey mystery of Andredesweald, which in those days came as far south as the top of Fairlight Hill, the people experienced a
certain splendid isolation. -Hastings and Neighbourhood, Walter Higgins, 1920
• If nothing can oppugn love
And virtue invious ways can prove,
What may he not confide to do
That brings both love and virtue too?
-Hudibras, Samuel Butler, 1662

The Storyline
Anna knew her mother's invious mind well and so knew better than to try to ferret out her true purpose in calling.

Origin:
Latin in- "not" + via "way, road" from Proto-Indo-European (PIE) *wegh-, which also gave Sanskrit vah-âmi "bring, lead," German Weg "way" and Wagen "wagon," and English "way" and "wagon."

Sources: Your Dictionary

Why This Word:
The road less traveled? No way! More the road not traveled. Invious can carry the sense both of untraveled or untravelable in a physical sense as well as inaccessible in more metaphorical sense. It should not be confused with envious, which isn't related etymologically. However, a brief scan of search results for invious found more uses as misspellings of envious than as the word itself.
And it's a shame. We need a word for the road not traveled.

Word-E: A Word-A-Day