südwestlich
southwest
Indicates a position or direction that lies to the southwest of a reference point.
Das nächste Dorf befindet sich etwa zehn Kilometer südwestlich von hier.
The nearest village is located about ten kilometers southwest of here.

southwestern / southwest
Loading your saved state.
southwest
Indicates a position or direction that lies to the southwest of a reference point.
Das nächste Dorf befindet sich etwa zehn Kilometer südwestlich von hier.
The nearest village is located about ten kilometers southwest of here.

The adjective 'südwestlich' (southwestern/southwest) is derived from the noun 'der Südwest' (the southwest) by adding the ending '-lich'. This is how all adjectives for compass directions are formed (e.g. 'nördlich' (northern/north of), 'östlich' (eastern/east of)).
Wir machen eine Wanderung in südwestlicher Richtung.
We are going on a hike in a southwesterly direction.
To describe the location of one place relative to another, 'südwestlich' (southwest of) is almost always followed by the preposition 'von' (of/from). It answers the question 'Wo?' (Where?).
Frankfurt am Main liegt südwestlich von Berlin.
Frankfurt am Main is located southwest of Berlin.
'Südwestlich' (southwestern) can stand before a noun like any other adjective. In that case, it must be declined accordingly.
Die südwestliche Küste der Insel ist besonders schön.
The southwestern coast of the island is especially beautiful.
western
'westlich' and 'südwestlich' both describe a direction or location. 'westlich' means only the direction west, or a location to the west of a reference point. 'südwestlich' is more specific and means the direction between south and west. The words can be confused because southwest also includes a western part. If you only want to say that something is in the west, 'westlich' fits. If it is also farther south, 'südwestlich' is more precise.

Südwestlich vom Bahnhof gibt es einen ruhigen Park.
Southwest of the train station there is a quiet park.
Am Montag sind wir in ein kleines Dorf westlich des Sees gefahren.
On Monday we drove to a small village west of the lake.