系列【けいれつ】
series, sequence, system, succession, keiretsu (group), conglomeration of businesses linked by cross-shareholdings, affiliated, subsidiary
体系【たいけい】
system, organization, organisation, architecture
系統【けいとう】
system, lineage, ancestry, family line, group (e.g. of colors) (colours), family (e.g. of languages), party, school (of thought), close (evolutionary) relationship, a population sharing a common ancestor (in genetics), strain (e.g. bacterial)
家系【かけい】
family lineage
日系【にっけい】
(of) Japanese descent, non-Japanese of Japanese descent, nikkeijin, company, etc. set up with Japanese capital, company managed by Japanese or non-Japanese of Japanese descent
生態系【せいたいけい】
ecosystem
系図【けいず】
family tree, pedigree, genealogy
直系【ちょっけい】
direct descent, direct line
水系【すいけい】
water system, river system, drainage system
系譜【けいふ】
genealogy, lineage, family tree, pedigree
山系【さんけい】
mountain range, mountain system
太陽系【たいようけい】
solar system
体系的【たいけいてき】
systematic
銀河系【ぎんがけい】
Milky Way galaxy, Milky Way, the Galaxy, galactic system, galaxy
神経系【しんけいけい】
nervous system
同系【どうけい】
affiliated, akin
系統的【けいとうてき】
systematic
大系【たいけい】
outline, survey, compendium