A departure usually of a large number of people 

S: flight escape, migration, hegira

A: arrival influx, immigration

Foreign; charmingly unfamiliar or strikingly unusual

S: alien: striking, extraordinary

A: native, indigenous, endemic; commonplace, familiar, ordinary

Expedient

a: Advantageous to one's interest or purpose.

b: An emergency course of action; a means to an end

S: convenient, timely, practical,; device scheme design stratagem maneuver stopgap

A: disadvantageous, unservicable, unsuitale

a. to use to the greatest possible advantage, often selfishly

b. A brillant or heroic deed

S: capitalize on; feat, heroics, coup, tour de France, derring-do

To explain in detail

S: clarify, eludicate, explicate, delineate,

A: summarize, abstract, synopsize

a: to assemble or sonstruct from seperate parts

b. to make up with the intention of decieving

S: produce, devise, manufacture, concoct, contrive, come up with, cook up

Not ment seriously: playful or humerous

S: waggish, whimsical,  joking, comic, frivolous, droll

A: serious, grave solemn, sober, earnest, humorless

a. an exact copy

b. reproduced exactly

S: replica, reproduction, duplicate

a. faulty reasoning: an error in logic

b. A false or mistaken notion

S: mistake, flaw, fault, defect, solecism

a.A unit of length roughly equal to six feet and used primarily in the measurements of marine depths

b. To get to the bottom of; to understand

S: sound, plump, prob, delve, penetrate, ferret out, root out: devine, grasp, comprehend

Unconsciously foolish, stupid, or absurd

S: inane, vacuous, vapid, nonsensical, laughable, silly, ridiculous, ludicrous: wacky, goofy

A: sensible, intelligent, perceptive, acute, incisive: judicous

Possible; both doable and workable

S: practicable, practical, usable, realistic

A: impossible, unworkable, impracticable, impractical

To pretend or to give a false apperence of

S: fake, sham, simulate

agreeably suited to the purpose or occasion; aptly or gracefully expressed

S: fake, sham, simulate

fettish

a. An objective believed amoung primitive peoples to have magical powers.

b. An object of unreasonably excessive attention or reverence

S: charm, amulet, tailsman: fixation, obsession, preoccupation, compulsion