復, 複 or 腹? The Radical Decides Which ふく You Need

Why do three different kanji sound the same?

Because they are built the same way. 復, 複 and 腹 are all 形声文字 — phonetic-semantic compounds. Each one is a radical plus the component 复, and 复 is doing exactly one job: supplying the sound ふく.

彳 + 复 = 復    衤 + 复 = 複    月 + 复 = 腹

This is not a coincidence you have to memorise three times. It is a rule of how the character set is constructed, and it means the shared half is the useless half for telling them apart. The half that matters is the one on the left.

What does each radical actually mean?

Read the table left to right and the meanings stop being arbitrary. 彳 is the radical of walking — 往, 待, 後 all carry it — so 復 is about going back over a road you already walked. 衤 is 衣 (clothing) squeezed into a left-hand slot; cloth is a thing you layer, so 複 is about layers and copies. 月 in this position is にくづき, the flesh radical you also see in 胸, 腕, 肩 — so 腹 is a body part.

復習 is walking back over ground you already covered. That is literally what reviewing is.

Which words use which?

Every word on the left involves something coming back. Every word in the middle involves more than one of something. Everything on the right is your abdomen. If a word you are unsure about does not fit one of those three buckets, you have the wrong kanji.

Where do learners actually get this wrong?

Not in reading — in writing and in multiple choice, where the four options look nearly identical on the page. This is one of our N4 items:

The options are 復修 / 複習 / 復習 / 腹習. Three of them are wrong in two different ways, and the difference is worth naming:

• 腹習 and 複習 are radical swaps — right sound, right phonetic component 复, wrong radical.
• 復修 is a different trap entirely: 修 and 習 both read しゅう, so the first kanji is correct and the second one is the homophone.

So the item punishes you twice for reading by sound alone. Reading by radical answers it in one step: the sentence is about doing something before a test, which is a going-back-over meaning, so 彳, so 復.

Can this predict other ふく kanji?

Yes, and this is where the habit pays off. ふく has a second phonetic family built on 畐, and it behaves identically — same phonetic, meaning assigned by the radical.

One common ふく kanji sits outside both families: 服 (clothes) is built on a different phonetic part, so it is not predictable from 复 or 畐 — learn it as its own word. Everything else you meet at N4 belongs to one of the two groups above.

You now have a procedure rather than a list. When a ふく kanji appears, ignore the right side — it is only telling you how to pronounce it — and ask what the left side is about. Cloth, blade, body, road, altar. The meaning follows from that.

The same procedure works far beyond ふく. 校, 械, 枝 all share 木 and are all about wood or wooden things; 語, 話, 読 all share 言 and are all about speech. The radical is the part of a kanji that was designed to be read for meaning.