I. sider noun
( -s )
Etymology: side (IV) + -er
obsolete : one that takes a side : an adherent of a person : a partisan of a cause
II. sid·er |sīdə(r) noun
( -s )
Etymology: side (I) + -er
: one placed or living in a usually specified side (as an area or section of a city) — used in combination
an east- sider