系

flight from science

Computing

number system

exogamy; outbreeding

Medicine

multiple-system atrophy; MSA

ignition system

Slang; From the name of user-submitted novel site 小説家になろう

Mary Sue novel; wish-fulfillment story

redundant system (string, line)

Computing

satellite link

matriarchy

Linguistics

phonological system; phoneme system

International System of Units; SI

Astronomy

trans-Neptunian object; transneptunian object; TNO

centimetre-gram-second system of units

impulse conduction system (of the heart)

collateral relation by blood

differential coefficient

river system

matrilineal family

Linguistics

systemic grammar

matrilineal emperor of Japan; emperor (either male or female) whose mother is (was) a member of the Imperial family but whose father is (was) not

Computing

time series analysis

Video games

roguelike (subgenre of role-playing video games)

systematics

paraphyletic