Titration may be *how* you go about diluting it -- if you have the finely-graded glass titration tube to do it with -- but it *is* not, per se, the same thing.
Not in general public usage, that is; the way you use it is probably quite valid in your specific sub-culture of biogeeks and chemonerds, where you've all probably forgotten, by now, that stuff can actually be diluted in ways other than by titration -- but fooling poor Greg to use it in *his* daily speech would be doing him a disservice.