The opposite of concise is "utilize"

Every word must be concise. This is why the word "utilize" must be avoided, even reviled. Why? Because the verb "use" gets the message across much faster and clearer than the three-syllable "utilize" -- which makes "utilize" cumbersome and unnecessary. Compare these two sentences:

Utilize our website today.

Use our website today.

The second sentence is stronger, crisper and more precise. In other words, clear writing isn't about showing off vocabulary or using 25 cent words; it's about using concise language to communicate clearly.

But don't take my word for it. Here's what Professor William Strunk, Jr. of Cornell University wrote in 1918 about gunking up sentences with unnecessary words and expressions:

Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts. This requires not that the writer make all his sentences short, or that he avoid all detail and treat his subjects only in outline, but that every word tell.

Many expressions in common use violate this principle:

the question as to whether -- whether (the question whether)
there is no doubt but that -- no doubt (doubtless)
used for fuel purposes -- used for fuel
he is a man who -- he
in a hasty manner -- hastily
this is a subject which -- this subject
His story is a strange one -- His story is strange.

In especial the expression the fact that should be revised out of every sentence in which it occurs.

owing to the fact that -- since (because)
in spite of the fact that -- though (although)
call your attention to the fact that -- remind you (notify you)
the fact that he had not succeeded -- his failure

And in our pursuit of concise writing, we should all add the unnecessary "utilize" to our list of words that should be revised out of every sentence.