wifi
n.a way of connecting computers and phones to the internet without using any cables. You use this to go online at home, in cafés, or at school.
n.a facility allowing computers, smartphones, or other devices to connect to the internet or communicate with one another wirelessly within a particular area. Often written as Wi-Fi.
“The hotel provides free wifi for all its guests.”
“I have to sit close to the router because the wifi signal is very weak in the bedroom.”
“Modern urban infrastructure increasingly treats high-speed wifi as a core utility, similar to water and electricity, because so many public services now require a digital connection to operate efficiently.”
As an uncountable noun, wifi does not take an indefinite article when referring to the service in general.