look up any word, like timebomb:
 
1.
A person who always under estimates the time necessary to do something or get somewhere.
"Hey, Cindy. you know my parents are expecting us in 20 minutes."
"No problem. I just have to wash the dishes, take a shower, do my hair, walk the dog and then I'm all good to go. See you in 15."
"You are such a chronoptimist! I'll see you in 45."
by annastella June 07, 2006
 
2.
Someone who always underestimates the time necessary to complete a task or project. Term introduced on the Handyman for the Common Man web-only TV show.
“Linda only scheduled three hours to shoot our first corporate video. What a frickin’ chronoptimist.”
by The Handy Writer May 10, 2009