Tactical is a great name. Assault rifle is a media, left wing propoganda moniker given these rifles. Is a Ruger 10/22 all tricked out in tactical furniture an assault rifle? Yup, if you listen to the left.
Actually, you need to blame Hitler. He chose the name 'storm (assault) rifle' for the Maschinenpistole 43.
The Sturmgewehr 44 is considered the 'grand daddy' of assault rifles. A select fire, intermediate cartridge rifle.
You can split hairs that civilian versions of the AR-15 don't have select fire, but you can still dump 30 rounds in less than 30 seconds in a six inch group at 100yds with very little practice. Good luck pulling that off with a bolt action.
I prefer the term “sport utility rifle”.