Proto-Indo-European root meaning "to follow."
It forms all or part of: associate; association; consequence; consequent; dissociate; ensue; execute; extrinsic; intrinsic; obsequious; persecute; persecution; prosecute; pursue; second (adj.) "next after first;" second (n.) "one-sixtieth of a minute;" sect; secundine; segue; sequacious; sequel; sequence; sequester; sociable; social; society; socio-; subsequent; sue; suit; suite; suitor; tocsin.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit sacate "accompanies, follows;" Avestan hacaiti, Greek hepesthai "to follow;" Latin sequi "to follow, come after," secundus "second, the following;" Lithuanian seku, sekti "to follow;" Old Irish sechim "I follow."
1610s (intransitive), from Latin litigatus, past participle of litigare "to dispute, carry on a suit," from phrase litem agere "to drive a suit," from litem (nominative lis) "lawsuit, dispute, quarrel, strife" (which is of uncertain origin) + agere "to set in motion, drive forward" (from PIE root *ag- "to drive, draw out or forth, move"). Transitive sense is from 1741. Related: Litigated; litigating.
1570s, "complete suit of armor," from Greek panoplia "complete suit of armor," from pan- "all" (see pan-) + hopla (plural), "arms" of a hoplites ("heavily armed soldier"); see hoplite. Originally in English figurative, of "spiritual armor," etc. (a reference to Ephesians vi); non-armorial sense of "any splendid array" is by 1829. Related: Panoplied.