Haircare is looking after the hair on your head: washing it, drying it, putting things in it, and shaping it. Shampoo, conditioner, hair masks, oils, and the time you spend at the sink or the salon all sit under this word. You will see it on bottles and in shops more than in chat — it is a bit of a “product” word, the name of an aisle. Though actually, English also writes it as two words, hair care, and that is just as normal; packing and ads like the one-word form. It is uncountable: you do not say “a haircare” or “haircares.” People talk about a haircare routine (what you do every week) or haircare products (the bottles). It is not only “making a pretty style.” Washing greasy hair, being gentle with damaged hair, and not burning it with a too-hot dryer are haircare too. Formal enough for a label; a friend is more likely to say “I need to wash my hair” than “I need to do haircare.”

護髮、頭髮保養（店裡常寫「護髮」）