As a verb siver
is (obsolete) to simmer.
As a noun sixer is
a cub scout who leads a group of six.
sixer
English
Noun
(
en noun)
A Cub Scout who leads a group of six.
* 1995 , Boy Scouts of Canada. National Council, The Cub Book
- Many packs have a sixer' s council where the sixers, and sometimes the seconds, meet with Akela and some of the other leaders.