平 píng is a pictograph of something flat and in balance. The early forms are read as the image of breath or sound spreading out evenly, or of a level surface with two marks rising equally on either side of a central stem. Whatever the precise picture, the felt sense is the same: a thing settled level, with nothing tilted higher on one side than the other. The modern glyph keeps that symmetry, a horizontal base crossed by an upright stem with a balanced stroke to each side. The simplified and traditional forms are identical.

From the image of the level surface grow four senses that fan across the language:

1. Flat, level, even. The literal meaning, a surface with no bumps: 平面 píngmiàn (a flat surface, a plane), 平地 píngdì (level ground), 平稳 píngwěn (steady; smooth).
2. Equal, fair. A balance where no side is weighted over another: 公平 gōngpíng (fair), 平等 píngděng (equality), 平均 píngjūn (average; even).
3. Peaceful, calm. A surface undisturbed, with no waves or strife: 和平 hépíng (peace), 平安 píngān (safe and sound), 平静 píngjìng (calm).
4. Ordinary, plain. Nothing rising above the common level: 平常 píngcháng (ordinary), 平凡 píngfán (commonplace), 水平 shuǐpíng (level; standard).

The thread through every sense is the level line. A floor with no bumps, a scale with no tilt, a sea with no waves, a life with no peaks: each is 平, something brought to an even plane where nothing stands out of place.

The fairness sense of 平 is the level line applied to people. A scale that hangs even, with neither pan dipping, is the oldest image of justice, and 平 carries it into a whole family of words about treating sides alike. 公平 gōngpíng pairs 平 with 公 gōng (public, impartial) for fairness in dealings and rules. 平等 píngděng pairs it with 等 děng (rank, grade) for equality of standing, the principle that no rank sits above another. 平均 píngjūn pairs it with 均 jūn (even) for the arithmetic average, the level a set of values would reach if shared out evenly.

The shared picture is the balanced scale. To be 公平 is to weigh without a thumb on either pan; to be 平等 is to stand on the same line as everyone else; to be 平均 is the number where all the weight evens out. Wherever 平 means fair, imagine the beam of a balance coming to rest dead level.

When the level surface is a sea, 平 means calm; when it is a life, 平 means ordinary. 和平 hépíng joins 和 hé (harmony) with 平 (calm) for peace, the absence of war and strife, the social water without waves. 平安 píngān joins 平 with 安 ān (safe; at ease) for being safe and sound, the wish travelers and families exchange. 平静 píngjìng joins 平 with 静 jìng (quiet) for an inner or outer calm.

The same flatness turns into plainness. 平常 píngcháng (ordinary, usual) and 平凡 píngfán (commonplace) describe what does not rise above the common level, the everyday rather than the remarkable. 水平 shuǐpíng, literally the level of water, names a standard or skill level, since still water finds one even line. Calm, ordinary, standard: each is the surface lying flat, with nothing breaking through.

Hold one image: a level line with nothing rising above it. That flat line is the whole character. Everything 平 means is some surface brought even, with no bump, no tilt, no wave, no peak.

Lay the line on the floor and it is flat ground (平地, 平面). Lay it across a balance and it is fairness, neither pan dipping (公平, 平等, 平均). Lay it on the sea and it is calm and peace (和平, 平安, 平静). Lay it across a life and it is the ordinary, the everyday that rises no higher than the common level (平常, 平凡). Whenever you meet 平, picture the line settling level, and ask what surface it has just made even.