名詞 aperture:

1. a device that controls amount of light admitted
2. a natural opening in something
3. an man-made opening; usually small

1. A separation, an aperture, a fissure, or a short passage in an organ or a body part.
   裂孔，孔器官或身體部位中的孔隙、隙縫、裂隙或通道
2. A lid or flap covering an aperture, such as the gill cover in some fishes or the horny shell cover in snails or other mollusks.
   鰓蓋覆蓋在一孔或縫隙上的蓋，如一些魚(yú)類的鰓或覆蓋在蛇或其它軟體動(dòng)物身上的角質(zhì)殼
3. What aperture are you using?
   你使用多大的光圈?
4. The aperture in the door is so wide.
   門上的孔隙太大了。

ap.er.ture

n.（名詞）
An opening, such as a hole, gap, or slit.
孔，洞：開(kāi)口，如洞、縫隙或缺口

A usually adjustable opening in an optical instrument, such as a camera or a telescope, that limits the amount of light passing through a lens or onto a mirror.
光圈：光學(xué)儀器上的一個(gè)可調(diào)開(kāi)口，如照相機(jī)或望遠(yuǎn)鏡，它控制穿過(guò)鏡頭的或到鏡面的光的數(shù)量
The diameter of such an opening, often expressed as an f-number.
孔徑：這種開(kāi)口的直徑，常以f數(shù)表示
The diameter of the objective of a telescope.
孔徑：望遠(yuǎn)鏡物鏡的直徑

來(lái)源：
Middle English
中古英語(yǔ)
from Latin apertôra
源自 拉丁語(yǔ) apertôra
from apertus [past participle of] aperore [to open] * see wer- 4
源自 apertus [] aperore的過(guò)去分詞 [開(kāi)，打開(kāi)] *參見(jiàn) wer- 4

【引伸】
ap.ertur.al
adj.（形容詞）