1. a dot or other small mark in writing or printing, used as a diacritic, punctuation, etc.
2. a very small part or quantity; a particle, jot, or whit
"Without adding a tittle, your 'i' will look like a vertically challenged 'l.'"
"I don't even have a tittle of interest in this class."
Origin: (from etymonline.com)
"late 14c., 'small stroke or point in writing,' representing Latin apex in Late Latin sense of 'accent mark over a vowel,' borrowed (perhaps by influence of Provençal titule 'the dot over -i-') from Latin titulus 'inscription, heading.'"