Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!

Qenya 

hamu-

verb. to sit down, take a seat

The verb ᴹQ. hamu- “sit down, take a seat” appeared in the Quenya Verbal System (QVS) of 1948 as an example of an inceptive verb based on ᴹQ. ham- “sit” (PE22/114).

Neo-Quenya: In Tolkien’s later writings the usual verb for “sit” was Q. har-, so I would update the 1948 verb hamu- to ᴺQ. haru- “to sit down, take a seat”.

Conceptual Development: The Qenya Lexicon of the 1910s had ᴱQ. {sosta- >>} sorta- “sit down” under the early root {ᴱ√SOŘO >>} ᴱ√SORO [ÐORO] (QL/85-86).