表 belongs to the 衣 yī (garment; clothing) family, and the original image is concrete and physical. The Shuōwén glosses 表 as an outer garment of fur, the kind worn with the hairy side facing out. In the oldest forms the 衣 element is split open and a 毛 máo (fur; hair) sits inside it, picturing exactly this: a pelt worn on the outside of the body. From the worn-on-the-outside fur coat comes the whole abstract career of the character. What is on the outside is the surface; the surface is what shows; what shows can be expressed; what is expressed can be laid out in a chart.

This is the thread that ties together five senses that look unrelated in an English dictionary. The outer surface (表面 biǎomiàn) is the fur facing out. The outward appearance (外表 wàibiǎo) is what that surface presents to the world. To express (表示 biǎoshì) is to bring an inner state to the surface where others can read it. A table or form (表格 biǎogé) lays information out on a flat surface for inspection. And to represent (代表 dàibiǎo) is to stand on the outside as the visible face of something larger. The garment worn outside is the seed of all of them.

The watch and the meter belong to a separate strand. In traditional writing, the instrument that displays a reading on its face, a clock, a wristwatch, a gauge, was written 錶 with the 金 jīn (metal) radical added, marking it as a metal device. Simplified Chinese dropped the metal radical and folded 錶 back into plain 表, so today 手表 shǒubiǎo (wristwatch) and 电表 diànbiǎo (electricity meter) are written with the same character as 表面 and 表示. The logic still holds underneath: a watch face or a meter face is, after all, a surface that displays a reading. When you read traditional texts from Taiwan or Hong Kong, expect 錶 for the timepiece and 表 for everything else.

One small family wrinkle sits on top of all this. 表 also marks relatives connected through a sister, a daughter, or a maternal line, the cousins who stand outside the patrilineal surname: 表哥 biǎogē (older male cousin on the mother's or a sister's side) and 表姐 biǎojiě (older female cousin of the same kind). They are the relatives on the outside of the家 jiā surname line, the same outer that runs through every other sense of the character.

Hold one image and the whole character organizes itself: a fur coat worn with the hairy side out. That is the literal origin of 表, the garment radical 衣 split open around a tuft of fur, the pelt facing the world. Everything else is what faces out. The outer surface of the lake (表面), the way a person looks at first glance (外表), the feeling you bring out so others can read it (表示, 表达), the act you put on for an audience (表演), the chart laid flat for inspection (表格), the watch face that shows the time (手表), the delegate who stands on the outside for the group (代表). One coat, worn outside, branching into a dozen everyday words.

Keep two practical splits in mind. First, the writing split: in traditional script the timepiece and the meter take an extra metal radical and are written 錶, while simplified Chinese folds them back into plain 表. If you switch between simplified and traditional texts, that is the one place 表 changes its coat. Second, the usage split between 表示 and 表达: you 表示 a stance with a single act, a nod or a stated position, while you 表达 your inner world with effort and skill. The first signals; the second articulates.

When 表 turns up in a new word, ask which branch it is on. Is something facing outward as a surface or appearance? Is an inner state being brought out and shown? Is information being laid out on a chart, or a reading displayed on a face? Is one thing standing on the outside for another? In nearly every case the answer is some version of the same root: the part that faces out. The fur worn outside is two and a half thousand years old, and it still tells you what 表 means.