Emphatically exhibits the sincerity of your seriousness. The classic use is to close a letter with it.
Dear Urban Dictionary:
Thank you in advance for considering “sinseriously” in your Urban Dictionary.
Were sinseriously to be included in The Urban Dictionary, that would make my day, perhaps even my week.
Sinseriously,
Cyprus Denton Fekks
Thank you in advance for considering “sinseriously” in your Urban Dictionary.
Were sinseriously to be included in The Urban Dictionary, that would make my day, perhaps even my week.
Sinseriously,
Cyprus Denton Fekks
by Cyprus Denton Fekks February 19, 2010

"sinseriously" is a super fun loving word that can be used to sign a card with. It is a great way to let someone know how much you care about them and that you are serious and sincere about everything you wrote on a letter. It is a cherry on top.
by valkayerie July 09, 2011

by LilRayRay August 18, 2008

the words sincere and serious together to indicate something such as a sentiment which is seriously sincere.
by George D T July 03, 2007

by Berjmaster November 27, 2015

a combination of the words sincere, and serious. used to convince someone that you mean what you say.
by bobillard richardsonly July 12, 2010
