The hashtag is ubiquitous in our Internet-centered society, but why do we call it that and what does the word really mean? For decades prior, it was known as a pound sign or number sign and the mathematical term is an octothorpe. Well, when Twitter first started using the symbol to group things in 2007, they renamed it the hashtag because "it just sounds catchier", and the rest was history. However, the word hashtag has been around a bit longer than all that; it was used in the late 1970s to program special keywords. This was called a hash tag because hash is an obscure word for "sign", ergo "sign tag" (it was originally going to be called a tag hash, or "tag sign"). This is the same hash as the potatoes but not the same as the drugs, as it comes from French hacher, meaning "to chop" (something you do to make both signs and hash browns). Through Middle French and Old French hacher, this can be traced back to Proto-Germanic hakkona, meaning "hack" (also the source of English hack, through Old English haccian and Middle English hakken/hacken), from Proto-Indo-European keg, or "to be sharp". Tag, meanwhile, has a surprisingly interesting etymology which I'll save for later.
Adam Aleksic, a freshman studying linguistics at Harvard University, has been described as the internet's sixth most famous etymologist. He has disturbing interests in words, vexillology, geography, board games, limericks, and law, and he loves writing about himself in the third person.
The Etymology Nerd