Chapter Indiscipline to In extremis of I by Soule's Synonymes

2. Implacable, unappeasable, inexorable, not to be appeased, irreconcilable.

Inexplicable, a. Unaccountable, unintelligible, incomprehensible, inscrutable, mysterious, strange, enigmatical, not to be explained.

Inexpressible, a.

1. Unutterable, unspeakable, indescribable. See Ineffable.

2. Surpassing, boundless, infinite.

Inexpressibles, n. pl. [Comic euphemism.] Unmentionables, breeches, trousers, pantaloons.

Inexpressive, a. Unexpressive, characterless, blank.

Inexpugnable, a.

1. Impregnable, unassailable, not to be taken by assault, not to be stormed, secure from capture, tenable against all odds.

2. Unconquerable, invincible, not to be subdued.

3. Incontrovertible, irrefragable, impregnable, unassailable, unanswerable.

Inexsuperable, a. Insurmountable.

In extenso. [L.] In full, to the full extent, at length, in full detail.

Inextinguishable, a. Unquenchable, that cannot be extinguished.

In extremis. [L.] In one’s last moments, at the point of death, in the very act of death, moribund.