Acronyms dictionary SIL or sil or sill [sil] or [es-ahy-el] What does SIL mean? SIL is an acronym for sister-in-law and son-in-law. Sil is sometimes used as internet slang for silly. Where does SIL come from? Examples of SIL Why would Sam put her sunglasses on to drive home?! It's nighttime cmon Sam don't be so sil @allison_boni, July, 2014 this weekend I told my SIL I have a wireLESS dachshund instead of a wirehaired dachshund. my dog can go everywhere! @Cyndy_Bush, December, 2009 You may think that not having your SIL present will decrease your stress and anxiety, but the truth is you won’t really be able to relax knowing that your MIL will be wondering why her daughter wasn’t invited to the party. HuffPost, December, 2014 SEE MORE EXAMPLES Who uses SIL? As a shortened form of silly, sil is more commonly seen as sill on social media, where it often has an affectionate or lighthearted connotation. SIL is still used in social media and popular online for sister-in-law and son-in-law for its convenience, often conveying a sense of intimacy and familiarity. While diverse men and women have used sil on Twitter this way, women have seemed to favor it for sister-in-law. However, it seems women tend to use it more frequently. Since Donald Trump’s presidential campaign and election in 2016, SIL has become increasingly used to refer to his controversial son-in-law and adviser, Jared Kushner. Just Added 4th of July, boogaloo, shelfie, ACAB, yeet Note This is not meant to be a formal definition of SIL like most terms we define on Dictionary.com, but is rather an informal word summary that hopefully touches upon the key aspects of the meaning and usage of SIL that will help our users expand their word mastery.