wifi
n. uncountablen. 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.
I need a wifiI need wifiAs an uncountable noun, wifi does not take an indefinite article when referring to the service in general.