Gnomish
biltha-
verb. to flutter, flit
feltha-
verb. to resemble, seem like; to seem likely, be probable
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!
The verb G. biltha- “flutter, flit” appeared in the Gnomish Lexicon of the 1910s, an elaboration of G. bil “bird” (GL/23).
Neo-Sindarin: Since G. bil “bird” is no longer used, for purposes of Neo-Sindarin I would alter this verb to ᴺS. gwilwa- “to flutter, flit”, inspired by Q. wilwa “fluttering to and fro”.