Quote Originally Posted by aerithsloveslave View Post
I always pronounced it Tie-dus as in tidal which I thought his name was based upon...
http://en.wikipedia.org/wiki/Tidus#Character_design
For his part, Character Designer Tetsuya Nomura has expressed that — after designing serious and moody main characters for Final Fantasy VII and Final Fantasy VIII — he wanted to give Tidus a cheerful attitude and appearance, which is reflected in the name Kazushige Nojima chose for him (Tiida is the Okinawan word for "sun"). He's also explained that he wanted his clothing and accessories to suggest a relationship with the sea. For example, his outfit bears a distinctive blue theme, and the symbol of Tidus' blitzball team — which appears on his clothing — is designed after a fishing hook, while also designed such that it's an amalgamation of the letters "J" and "T" (the first letters of Tidus' name and that of his father, Jecht).
And thus spoke Wikipedia, <cite class="book" style="font-style: normal;">Sam Kennedy and Gary Steinman Official U.S. PlayStation Magazine August, 2001 (in English) </cite>and Tetsuya Nomura 20s. FLAREgamer

So his appearence is reminscent of the sea, but his name's origins are rooted in the sun.