I second that "Geysir" is the name of a specific gushing spring in Iceland, which did indeed gush a long way up into the air until fairly recently, when it lost a lot of its power and now is only half the man jet it used to be. The name spread to all springs that intermittently fire hot water into the sky, and from there to water heaters in bathrooms, and to old men who intermittently hold forth with a lot of hot air - so in that way a geezer is still a geyser.
I would agree, though, that they are now spelt differently. Maybe that is because those referring to old men as geezers were not familiar with the Icelandic spelling and spelt it as it sounds?
QUORDLE, 12 March š§š§š§š§š§