Lagosian adjective 1noun 1forms 3 adjective1 •Of or relating to Lagos in Nigeria. noun1 •A native or inhabitant of Lagos in Nigeria.If the sun were going down, it meant there would be no light soon and Lagosians needed to see their way. Street lights here did not always function. — 2005 formsLagosians · more Lagosian · most Lagosian