prefix
Etymology: Latin, from cis — more at he
1. : on this side : on the nearer side — often joined to second element with a hyphen
cis alpine
cis -Alleghany
— compare trans- , ultra-
2. : nearer in time : since
cis atomic
3. usually italic : cis
cis -dichloro-ethylene
— opposed to trans- ; see cis-trans isomerism