eager

• adj.熱心な; 熱心な; 熱心な
• n.（熱心な）人の名前；（英）イーグル

ac（尖った、とがった）の語源で、語源的にはacid（酸）、acumen（洞察力）と同じ。

eager

eager: [13] As its close etymological connection with vinegar and acid might suggest, the underlying sense of eager is ‘sharp’. It comes ultimately from the Indo-European base *ak- ‘sharp, pointed’, amongst whose other English descendants are acne, edge, and oxygen. It was the source of Latin ācer ‘keen, sharp’, which was used in relation both to sight, hearing, etc, and to temperamental qualities – hence ‘ardent, zealous’.

The Latin adjective (from which English also gets acid and acrid) became *acrum in post-classical times, and from this came Old French aigre (source of the -egar of vinegar), which passed into English via Anglo- Norman egre. English retained the literal senses ‘pungent, sour’ and ‘sharp-edged’ until the early 19th century.
=> acid, acne, acrid, acute, edge, oxygen

eager (adj.)

late 13c., "strenuous, ardent, fierce, angry," from Old French aigre "sour, acid; harsh, bitter, rough; eager greedy; lively, active, forceful," from Latin acrem (nominative acer) "keen, sharp, pointed, piercing; acute, ardent, zealous" (see acrid).

Meaning "full of keen desire" (early 14c.) seems to be peculiar to English. The English word kept a secondary meaning of "pungent, sharp-edged" till 19c. (as in Shakespeare's "The bitter clamour of two eager tongues," in "Richard II"). Related: Eagerly; eagerness. Eager beaver "glutton for work" [OED] is from 1943, U.S. armed forces slang.

1. He is always eager for new experiences and ever-willing to experiment.

彼は常に新しい経験を持ち、そして永遠に試したいと望んでいる。

2.Robert was eager to talk about life in the Army.

ロバートは陸軍生活について話したいと思っています。

3.At first the eager young poet was a partisan of the Revolution.

最初、熱意に満ちた若い詩人は革命の強固な支持者だった。

4.But Jules was not eager for classroom learning，he hungered for adventure.

しかし、ジュルスは授業中に座って勉強することに熱心ではなく、冒険を渇望している。