exteriorl
ExTERIORL is not recognized as a standard English word in major dictionaries or widely used reference sources. It appears to be either a misspelling of exterior or a nonstandard form encountered in limited contexts. Because there is no established definition, the term lacks a stable, widely accepted meaning.
In architecture, the closest and well-defined term is exterior, which refers to the outward-facing parts of
In other technical fields, exterior has specific meanings that are unrelated to any supposed term exteriorl.
Usage notes: if you mean the outer or outside aspect of something, the correct word is exterior.