Hello (first attestit in 1833), frae holla, hollo (attestit 1588). This variant o hallo is eften creditit tae Thomas Edison as a coinage for telephone uise, but its appearance in print predates the invention o the telephone bi several decades.
The greetin hello is amang the maist generic an neutral in uise. It mey be heard in nearly aw social situations an in nearly aw walks o life, an is unlikly tae cause offense.