Moving or pointing towards the southwest. It works two ways. As an adverb it tells you the direction of movement: the storm moved southwestward. As an adjective it sits before a noun and describes something aimed that way: a southwestward course, the southwestward drift of the sand. This is a formal, written word. You meet it in weather reports, sailing and flying instructions, geography books and news writing — almost never in ordinary talk. If a friend asks which way you are going, you would say "we're heading southwest", not "southwestward". The -ward ending adds the idea of facing or travelling towards, so southwestward keeps your attention on the journey rather than the place; compare "we sailed southwest" (plain direction) with "we sailed southwestward for three days" (a long movement in that direction, which is where the word feels most at home).

向西南方（書面語；口語直接說 head southwest 就好）