Is conjunction a word in which letter or letters have been omitted?

Yes, "conjunction" is a word where letters have been omitted.

Original Word: conjunctio (Latin)

Omitted Letters: n

The word "conjunction" is derived from the Latin word "conjunctio," which means "a joining together." The letter "n" was dropped from the word in Middle English.

This is a common occurrence in English, where words have evolved over time and letters have been added, deleted, or changed.