Etymology
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are (v.)
present plural indicative of be (q.v.), from Old English earun (Mercian), aron (Northumbrian), from Proto-Germanic *ar-, probably a variant of PIE *es- "to be" (see am). Also from Old Norse cognates.

In 17c. it began to replace be, ben as first person plural present indicative in standard English. The only non-dialectal survival of be in this sense is the powers that be. But in southwest England, we be (in Devonshire us be) remains non-standard idiom as a contradictory positive ("You people aren't speaking correct English." "Oh, yes we be!"), and we be has reappeared in African-American vernacular.
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are (n.)
metric unit of square measure, 10 meters on each side (100 square meters), 1819, from French, formed 1795 by decree of the French National Convention, from Latin area "vacant piece of ground" (see area).
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art (v.)
second person singular present indicative of be; Old English eart. Also see are (v.). It became archaic in the 1800s.
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am (v.)
first person singular present indicative of be (q.v.); Old English eom "to be, to remain," (Mercian eam, Northumbrian am), from Proto-Germanic *izm(i)-, from PIE *esmi- (source also of Old Norse emi, Gothic im, Hittite esmi, Old Church Slavonic jesmi, Lithuanian esmi), first person singular form of root *es- "to be."

In Old English it formed only present tenses, all other forms being expressed in the W-BASE (see were, was). This cooperative verb is sometimes referred to by linguists as *es-*wes-. Until the distinction broke down 13c., *es-*wes- tended to express "existence," with beon meaning something closer to "come to be."

Old English am had two plural forms: 1. sind/sindon, sie and 2. earon/aron. The s- form (also used in the subjunctive) fell from English in the early 13c. (though its cousin continues in German sind, the 3rd person plural of "to be") and was replaced by forms of be, but aron (see are) continued, and as am and be merged it encroached on some uses that previously had belonged to be. By the early 1500s it had established its place in standard English.
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goldfish (n.)
1690s, from gold (adj.) + fish (n.). The fish were introduced into England from China, where they are native. A type of carp, they are naturally a dull olive color; the rich colors (also red, black, silver) are obtained by selective breeding. Goldfish bowl, figurative of a situation of no privacy, was in use by 1935.
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battlement (n.)
"an indented parapet in fortifications," early 14c., from Old French bataillement, earlier bastillement "fortification," from bastillier "to fortify, to equip with battlements," from bastille "fortress, tower" (see bastion). The raised parts are cops or merlons; the indentations are embrasures or crenelles.
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meek (n.)
"those who are meek," c. 1200, from meek (adj.).
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chromatopsy (n.)

 also chromatopsia, "color-vision, abnormal condition in which things are seen unnaturally colored or sensations of color are independent of natural cause," 1849, from chromato- + -opsy, from Greek opsis "a sight" (from PIE root *okw- "to see") 

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geologist (n.)
1795, from geology + -ist. Alternatives are geologer (1822); geologian (1837).
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polarity (n.)

1640s, "the having two opposite poles," originally of magnets, from polar + -ity. The sense of "variation in certain physical properties so that in one direction they are the opposite of what they are in the opposite direction" is from 1670s.

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