Select the most appropriate one-word substitution for the given group of words.

Something which is impossible to stop or prevent.

Inexorable

The most appropriate one-word substitution for "something which is impossible to stop or prevent" is inexorable.

• Merciful means showing kindness or compassion.
• Anagram is a word or phrase formed by rearranging the letters of another word or phrase.
• Eulogy is a speech or piece of writing praising someone who has died.

The word inexorable