 From the central idea of "tree", which is thin, tall, and spreading, comes an extension to other long or extended things or parts of things, such as "mwavuli" 'umbrella', "moshi" 'smoke', "msumari" 'nail'; and from activity there even come active instantiations of verbs, such as "mfuo" "metal forging", from "-fua" "to forge", or "mlio" "a sound", from "-lia" "to make a sound".Words may be connected to their class by more than one metaphor.For example, "mkono" is an active body part, and "mto" is an active natural force, but they are also both long and thin.