insondable

unfathomable, bottomless

adjective an-sohn-DABL Rare

Origin: From in- (not) + sonder (to sound, to probe depth) + -able.

Also means

inscrutable, impenetrable

Usage Note

Insondable is used both literally (an unfathomable abyss) and figuratively (an inscrutable mystery or an impenetrable personality). It is invariable by gender. A close synonym is inscrutable; the contrast with sondable (plumbable) is rarely used. Often encountered in literary or philosophical contexts.

Examples

"Le mystère restait insondable pour les enquêteurs."

Natural Translation

The mystery remained unfathomable to the investigators.

Free starter pack

Building your French vocabulary?

Get the 100 most common French words as a free PDF — one email, no spam.

Related Words

Explore French by topic

FrenchNow

French Numbers 1 to 100: Count With Confidence

French numbers 1 to 100 in one complete chart, with pronunciation, the et-un rule, hyphens, and the four-twenties system explained so you can count anywhere.

June 4, 2026 6 min read

FrenchNow

Faire in French: To Make, To Do, and More

Faire in French means more than make and do: master faire vs rendre, weather and sports idioms, the causative, and the mistakes English speakers make.

June 4, 2026 6 min read

FrenchNow

French False Friends: 25 Faux Amis to Avoid

French false friends look like English words but mean something else: actuellement is not actually, sensible means sensitive. Here are 25 faux amis to avoid.

June 3, 2026 5 min read

FrenchNow

French Liaison Rules: When to Link Words (and Not To)

French liaison links a silent final consonant to the next vowel. Learn the obligatory, forbidden, and optional rules, plus the s→z and d→t sound shifts.

June 4, 2026 5 min read