活 is a pictophonetic compound: 氵 (the water radical) carries the meaning, and 舌 shé (tongue) supplies the sound. On the left runs the three-drop water radical 氵, the standard form of 水 shuǐ when it stands beside another component. On the right sits 舌, the tongue. The water is the heart of the character; the tongue was borrowed for its old pronunciation, close to the sound that became huó.

The original image was a stream in motion. In the Shuōwén the graph is glossed in terms of flowing water, the gurgle and rush of a current that never stands still. A river runs, a spring bubbles, water moves: and moving water is the oldest emblem a writing system could reach for when it wanted to say alive. What flows is living; what sits stagnant is dead. From that single perception the whole character grows.

From flowing water two families of meaning open out. First, to live, to be alive. The thing that breathes and moves is 活 as against 死 sǐ (dead): 活着 huózhe (to be living), 生活 shēnghuó (to live, life), 活下去 huó xiàqù (to go on living). Second, living, lively, animated. Not bare survival but the quality of liveliness, the quickness of something that flows freely: 活泼 huópo (lively), 灵活 línghuó (nimble, flexible), 活力 huólì (vitality).

A third, very concrete sense grew in everyday northern speech: 活 as a piece of manual work, a job, the task in front of your hands. 干活 gànhuó means to do work, and 活儿 huór (with the retroflex ending) is the work itself: the carpenter's 活儿, the day's 活儿. The thread is the same flow of energy, now poured into the hands and the task. Japanese took the character as 活 (katsu) for liveliness and activity, surviving in 活動 (katsudō, activity) and 生活 (seikatsu, daily life).

The second family carries the water image forward into the quality of liveliness. A current that runs freely is quick, supple, full of energy, and 活 lends all of this to character and motion. 活泼 huópo describes a lively, animated person, most often a child, the opposite of dull or withdrawn. 灵活 línghuó is the same freedom applied to the body or the mind: nimble, adaptable, able to change course like water finding a new channel.

From there it powers a cluster of vitality words. 活力 huólì is energy and vigor, the vitality of a person or a city; 活跃 huóyuè is to be active, brisk, animated, the verb for a lively atmosphere or a busy market. Even 活动 huódòng, the everyday word for an activity or event, is built from 活 (lively) plus 动 (to move): a stirring, a thing in motion. Wherever Chinese wants to name energy in flow rather than mere existence, 活 is the character that does it.

The third sense is purely colloquial and very Chinese: 活 as a piece of manual work, the task your hands take on. In everyday northern speech 活儿 huór (with the retroflex 儿 ending) is the work itself, the concrete job: a tailor's 活儿, the farmer's 活儿, a hard day's 活儿. To do work is 干活 gànhuó, where 干 gàn means to do or to labor. This is the language of the workshop and the field, not the office, and it keeps the old energy of the character: living force poured into the hands.

Picture a stream running over a tongue. On the left, the three drops of the water radical 氵 are the current itself, splashing downhill. On the right, 舌 the tongue is the rock the water tumbles across, the part that was only ever borrowed for its sound. Hear the gurgle: that rushing, living water is the whole meaning. What flows is alive; what sits still is dead.

Now follow the water. Let it pool into a life and you have 生活, daily living. Let it run quick and bright and it becomes 活泼 (lively) and 灵活 (nimble), water finding any channel. Let it stir a crowd into motion and it is 活动, an activity. And let it pour down into the hands at a workbench and it is 活儿, the day's work, 干活. The drops on the left never stop moving: every sense of 活 is some shape of that flow, from being alive, to being lively, to the labor your hands are alive with.