Butto (Pagoda) (仏塔)
A pagoda is a Buddhist building derived from the ancient Indian stupa.
The Sanskrit word 'stupa' was transliterated into Japanese as 'sotoba' and this became abbreviated to 'toba' and simply 'to.'
A stupa is a mound-like structure containing Buddhist relics which was transmitted to China during the Han Dynasty and became influenced by the architecture of the wooden buildings of the time. It was during this period that the word 'to' became used to describe stupa. The stupa later made its way to Japan. Many pagodas in Japan including the five-storey, three-storey and two-storey forms are made of wood (such as Japanese cypress). Despite the wide variation of shapes, all retain the significance of the original stupa. A large number were constructed using funds donated by Buddhist followers.
To
To' is an abbreviation of 'sotoba' or 'toba' and originally referred to five-storey and three-storey pagodas but came to refer to any tall, narrow structure which tapers to a point at the top such as Tokyo Tower.
Soto/tasoto
The words 'soto' and 'tasoto' often refer to pagodas with two or more storeys such as two-storey, three-storey or five-storey pagodas/
Relatively short pagodas such as three-storey and five-storey varieties are often made of wood but many of the taller ones such as the thirteen-story pagoda at Tanzan-jinja Shrine are made of stone. There are also small three-storey and five-storey pagodas that are placed in gardens.
Tacchu
The word 'tacchu' originally referred to the 'to no hotori' (grave of a temple founder or high priest) erected by the disciples of a founding priest or Zen temple high priest following his death, or a small temple constructed in the grounds of a larger Zen temple. Tacchu' as well as the word 'toin' later came to refer to a sub-temple built within the grounds of another temple to serve as the residence of a high priest in his retirement. The word 'tacchu' is also written using alternative characters.
In Chinese Zen temples, it was originally the practice that the head priest would reside with the monks at the eastern or western so-do hall after he retired. As time passed and small temples were built within the grounds of larger temples, these became inhabited but these were limited to a single Zen monk per building.
This Chinese custom reached Japan and these buildings came to be seen as permanent sub-temples that served as the graves of individuals, such as the founding priest, who were particularly important to a Zen temple to create the uniquely Japanese concept of the 'tacchu.'
There were also tacchu that acquired their own patron and estate, and were kept running by the disciples.