simple

• adj.単純な; 無邪気な; ナイーブな
• n. a simpleton; a fool; a foolhardy person; a low birth.
• n. （単純な）人名；（仏語で）サンプラー

古フランス語のsimple（単純な、単純な）から、ラテン語のsimplex（単純な、単純な）から、PIE*sem（1つの、語源的には同じ）から、-plex（複数の、語源的には三重の、複雑な、拡張による）から。

simple

simple: [13] Etymologically, simple denotes ‘same-fold’ – that is, not multifarious. It goes back ultimately to a compound formed from prehistoric Indo-European *sm-, *sem-, *som- ‘same’ (source also of English same, similar, single, etc) and *pl- ‘fold’ (source of English fold, ply, etc). This passed into Latin as simplus ‘single’, which found its way into English via Old French simple.
=> fold, ply, same, similar

simple (adj.)

c. 1200, "free from duplicity, upright, guileless; blameless, innocently harmless," also "ignorant, uneducated; unsophisticated; simple-minded, foolish," from Old French simple (12c.) "plain, decent; friendly, sweet; naive, foolish, stupid," hence "wretched, miserable," from Latin simplus, variant of simplex "simple, uncompounded," literally "onefold" (see simplex). Sense of "free from pride, humble, meek" is mid-13c. As "consisting of only one substance or ingredient" (opposite of composite or compounded) it dates from late 14c.; as "easily done" (opposite of complicated) it dates from late 15c.

From mid-14c. as "unqualified; mere; sheer;" also "clear, straightforward; easily understood." From late 14c. as "single, individual; whole." From late 14c. of clothing, etc., "modest, plain, unadorned," and of food, "plain, not sumptuous." In medicine, of fractures, etc., "lacking complications," late 14c. As a law term, "lacking additional legal stipulations, unlimited," from mid-14c.

In Middle English with wider senses than recently, such as "inadequate, insufficient; weak, feeble; mere; few; sad, downcast; mournful; of little value; low in price; impoverished, destitute;" of hair, "straight, not curly." As noun, "an innocent or a guileless person; a humble or modest person" (late 14c.), also "an uncompounded substance." From c. 1500 as "ignorant people."

1. The letter was short-a simple recitation of their problem.

手紙は短く書かれている--簡単に彼らの問題を話しただけだ。

2.Though off-puttingly complicated in detail，local taxes are in essence simple .

地税は細部において非常に複雑だが、本質的には簡単である。

3.The room remains simple with bare,stippled green walls.

部屋は依然としてシンプルで、四方には水玉が飾られた緑の空の壁が広がっている。

4.Sadly，the film is let down by an excessively simple plot.

残念ながら、あまりにも簡単なプロットはこの映画を圧倒した。

5. "But Peter, it's not that simple ," Goldstone countered in a firm voice.

「でも、ピーター、ことはそんなに簡単ではありません」とゴッドストーンは語気を強めて反論した。