What is the opposite of an ending word?

The opposite of an ending word depends on what you mean by "ending word."

Here are some possibilities:

* Beginning word: This is the most straightforward opposite, referring to the first word in a sentence or passage.

* Starting word: This is similar to "beginning word" but can also refer to the first word of a new idea or thought.

* Initiating word: This emphasizes the act of starting something.

* Introductory word: This emphasizes the role of a word in introducing something.

The best opposite for "ending word" depends on the specific context.