mid-14c., "execution or completion (of an act)," from Old French efet (13c., Modern French effet) "result, execution, completion, ending," from Latin effectus "accomplishment, performance," from past participle stem of efficere "work out, accomplish," from assimilated form of ex "out" (see ex-) + combining form of facere "to make, to do" (from PIE root *dhe- "to set, put"). From French, borrowed into Dutch, German, Scandinavian.
From late 14c. as "power or capacity to produce an intended result; efficacy, effectiveness," and in astrology, "operation or action (of a heavenly body) on human affairs; influence." Also "that which follows from something else; a consequence, a result." From early 15c. as "intended result, purpose, object, intent." Also formerly with a sense of "reality, fact," hence in effect (late 14c.), originally "in fact, actually, really." Meaning "impression produced on the beholder" is from 1736. Sense in stage effect, sound effect, etc. first recorded 1881.
"to produce as a result; to bring to a desired end," 1580s, from Latin effectus, past participle of efficere "work out, accomplish" (see effect (n.)). Related: Effecting; effection; effectible.
Old English side "flanks of a person, the long part or aspect of anything," from Proto-Germanic *sīdō (source also of Old Saxon sida, Old Norse siða, "flank; side (of meat); coast," Danish side, Swedish sida, Middle Dutch side, Dutch zidje, Old High German sita, German Seite), from adjective *sithas "long" (source of Old English sid "long, broad, spacious," Old Norse siðr "long, hanging down"), from PIE root *se- "long; late" (see soiree).
The "long part of anything" sense is preserved hillside, it also was in 16c.-17c. side-coat "long coat." From 14c. as "lateral half of the body of a slaughtered animal." In reference to bacon, it indicates position relative to the ribs. The meaning "a region, district" is from c. 1400, as in South Side, countryside.
The figurative sense of "position or attitude of a person or set of persons in relation to another" (as in choose sides, side of the story) is recorded by mid-13c. As "an aspect" of anything immaterial (the bright side, etc.), by mid-15c.
The meaning "one of the parties in a transaction" is from late 14c.. The sense of "one of the parties in a sporting contest or game" is from 1690s. The meaning "music on one side of a phonograph record" is attested by 1936. As short for side-dish, by 1848.
The phrase side by side "close together and abreast, placed with sides near together" is recorded from c. 1200. Colloquial on the side "in addition," especially "unacknowledged," with connotations of "illicit, shady," is by 1893.
late Old English, "long, broad, spacious; extending lengthwise," from side (n.). Compare Old Norse siðr "long, hanging down." From late 14c. as "being from or toward the side," hence also "subordinate." Also "apart from the main course" of anything, as in side-road (1854); side-trip (1911). In side-eye (by 1922) the notion is "directed sideways."