The word Kimono is Japanese, in English it means wearing things. Though the garment everyone associates with Japan was not always called by that name, its long history is one of the best examples of how clothing confers a sense of identity.
The first ancestor of the kimono was born in the Heian period (794-1192). It was a square of fabric sewn together to create a garment that fit every sort of body shape. It was easy to wear and infinitely adaptable. By the Edo (in Japan) period (1603-1868) it had evolved into a unisex outer garment called kosode. Which literally mean small sleeves. The kosode was characterized by smaller armholes. It was only from the Meiji period (1868-1912) onwards that the garment was called kimono.
Kimono has undergone a different transformation in outlook. Different designers have created their own version of the kimono, the sleeve, and length are not static anymore, innovative styles have been made of the kimono.
You can choose to tweak your kimono in the way that suits your style but a kimono is ultimately a long free gown worn over another piece of clothing.