c. 1600, "peculiar person, person of a type seldom encountered," from Latin rara avis, literally "strange bird," from rara, fem. of rarus "rare" (see rare (adj.1)) + avis "bird" (see aviary). Latin plural is raræ aves. A phrase used of Horace's peacock (a Roman delicacy), Juvenal's black swan ("Rara avis in terris, nigroque simillima cygno"). A figure perhaps natural to the superstitious Romans, who divined by bird-watching.
traditional English dance of persons in costume, mid-15c., moreys daunce "Moorish dance," from Flemish mooriske dans, from Old French morois "Moorish, Arab, black," from More "Moor" (see Moor). It is unknown why the English dance (which typically is based on the Robin Hood stories) was called this, unless it is in reference to fantastic dancing or costumes (compare Italian Moresco, a related dance, literally "Moorish;" German moriskentanz, French moresque).
"right of each citizen to liberty, equality, etc.," 1721, American English, from civil in the sense "pertaining to the citizen in his relations to the organized commonwealth or to his fellow citizens." Specifically of black U.S. citizens from 1866, in reference to the Civil Rights Bill, an act of Congress which conferred citizenship upon all persons born in the United States, not subjects of other powers, "of every race and color, without regard to any previous condition of slavery." Civil Rights Movement in reference to the drive for racial equality that began in U.S. in mid-1950s is attested by 1963.
Rarely are we met with a challenge, not to our growth or abundance, or our welfare or our security, but rather to the values and the purposes and the meaning of our beloved nation. The issue of equal rights for American Negroes is such an issue. And should we defeat every enemy, and should we double our wealth and conquer the stars, and still be unequal to this issue, then we will have failed as a people and as a nation. [Lyndon Johnson, speech introducing Voting Rights Act, March 15, 1965]