I had my doubts about whether this word of Sesotho origin (South African) was used in English, but it seems that it was, and with a very similar sense since it is "community work, in a team, for the good of the social group", although within capitalist culture it is applied more to the work group, in order to achieve a goal. Letsema was in principle the time of harvest or any cultivation work, which in African villages was done together no matter who owned the land.
