在20世纪之前,首字母缩略词很罕见。它的广泛使用,或许与一二战有关。有时候即使本名改了,缩略词仍然不改,比如CDC换过好几个名字:Communicable Diseases Center——Centers for Disease Control——Centers for Disease Control and Prevention。DVD也类似:Digital Video Disc——Digital Versatile Disc。UNICEF也改过名:United Nations International Children's Emergency Fund——United Nations Children's Fund。有些词作为几个大写字母的组合根本不是纯粹的对应,比如BMX来自bicycle motocross,quango来自quasi-non-governmental organization。
PIN是personal identification number,但也有PIN number这种重复,类似的现象还有不少。缩略词也有矫揉造作的,比如Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act,缩写USA Patriot Act。