I revise cover letters for my clients all the time (at no additional cost too), and this is one of the most frequent errors I see when they're submitting a manuscript.
Typically, the first sentence in a cover letter will say something along the lines of:
We are pleased to submit our research article, entitled "The Mating Habits of the Tsetse Fly," for consideration of publication in Insects Today."
So what's the problem here? The word "entitled" essentially means to deserve something. So for example you're entitled to basic human rights. You're entitled to respect. The word can also have a negative connotation, as in "That brat is so entitled."
So basically, "entitled" is the completely wrong word to use in the context of a manuscript submission cover letter. It's an innocent mistake and it's easy to fix.
The appropriate word is actually "titled," which means to be named.
So the correct usage in the first line of a cover letter would be:
We are pleased to submit our research article, titled "The Mating Habits of the Tsetse Fly," for consideration of publication in Insects Today."
Side Note: The title of the journal should be placed in italics.
It is a standard convention to italicize the name of journals, newspapers, books, and other publications.