in·su·la \ˈin(t)s(y)ələ, ˈinshə-\noun (pluralinsu·lae \-ˌlē, ˈin(t)səˌlī\) 1.[Latin, literally, island — more at isle]: an ancient Roman building or a group of buildings standing together forming a block or square and usually constituting an apartment building 2.[New Latin, from Latin]: island of reil