Bonsai is a small tree in a shallow container
The short version would be: Bonsai is a Japanese word, which translates roughly to “Little tree in a shallow container”. When this is taken as the definition, everyone would be forgiven to then take a little woody plant, and put it in a bonsai pot and call it a bonsai. It is however a little more complex than this. As every person who has ever learned a second language knows: Translating the meaning of a term can mean more than just translating the word. Often there is a deeper meaning, which is not conveyed in the literal word-to-word translation.
Bonsai is a small TREE in a shallow container
Let’s try and rephrase our translation, and put some emphasis on a specific word. If we put the spotlight on one word, it may become a bit clearer: “Little TREE in a shallow container”. See what I did? I made the tree the focal point. Important to note, it is TREE, and not TREE-Species.
So, we are working on little trees. Or better yet, plants that look like trees. In itself, the species of the plant is of less importance than the image portrayed. A bonsai represents a tree in miniature. And the little tree is (typically) planted in a shallow tray.
Bonsai is a small TREE in a container that looks like a large tree
So the idea is to develop a plant in a way that for all visual cues, you have a miniature tree. With nice strong surface roots, a strong trunk, and finely developed branches with lots of twigs and leaves. All in balance and proportion in a way that if you took a picture, it could almost be mistaken for a life-sized tree.
Bonsai is a small TREE in a container that looks like an ancient large tree
Most bonsai are created to furthermore represent an ancient tree. So a tree that has seen hardship. With well-developed mature bark all the way up the branches. Without any clear marks of tools or human intervention. A tree that even upon close scrutiny, does not reveal the process that created it.
This means that developing a bonsai is a process that takes a lot of time. And time is the only way to really get a bonsai. Instant bonsai d o not exist, even though you could get this impression from some of the video’s and demonstrations you can run into. In some Japanese nurseries they work on trees that have been grown specifically for bonsai over several generations; So yes. Over 50-100 years!