FW and SS mean Fall/Winter and Spring/Summer.
The FW and SS mostly commonly stand for Fall/Winter and Spring/Summer or even Autumn/Winter in the fashion industry.
For fashion industry meanings of FW and SS.
FW (Fall/Winter) refers to clothing collections that are for colder weather, which features heavier materials such as cashmere, wool, layered garments and darker color palettes.
These lines of clothing are often presented around February to March.
SS (Spring/Summer) refers to clothing collections that are designed for warmer weather, featuring lightweight fabrics, brighter colors, and short sleeved or even open styles.
These lines of clothing are also often showcased on the runway around the months of September to October of the previous year.
Brands of clothing often also usually pair these abbreviations with a 2 digit year, such as SS24 or FW25 to designate the release cycle.
There are also alternative meanings of FW and SS in slang and other contexts which include:
FW (Slang), where in text messaging and social media, "fw" often stands for the slang phrase "fck with"* (meaning to like, appreciate, or vibe with someone or something), or can even mean "forward" in emails.
SSFW (Acronym), in other contexts, SSFW can mean Spring, Summer, Fall, Winter combined, or Sorta Safe for Work internet slang.