Draw a wave crossing a page, up and down and up again. The gap from one peak to the next is the whole word: wave plus length. Everything else is that measurement put to work. Give each radio station its own stretch of wave, and turning the dial becomes hunting for a wavelength. Then treat two people as two radios, and being on the same wavelength is what happens when both are set to the same place and every signal comes through clean.
在紙上畫一條波，上去、下來、再上去。從一個波峰到下一個波峰那一段距離，就是這個字的全部：wave（波）加 length（長度）。其他兩個意思，都是把這個測量拿去用。把每個電台分到一段波，轉旋鈕就變成「找波長」。再把兩個人當成兩台收音機，調到同一個波長，一邊發什麼另一邊都收得到——這就是 on the same wavelength。可以想成一把尺，先量物理，再量人。
From the word’s history
Wavelength is simply wave plus length: the length of one wave. The compound still says its own definition out loud.
wavelength 就是 wave 加 length：一個波的長度。這個複合字到今天還把自己的定義寫在臉上，所以最物理的那個意思一直是它的中心。
Wiktionary entry 'wavelength' (source_ref kaikki:3f6f69a190036ae4:808686184:29075): 'From wave + length.'
登入就可以看每一支怎麼連回核心畫面。