We have "ЛИСТ" - n. a leaf; "ПАДать" - v. to fall; and the letter "o" to unite the both words => "листопад" - a fall of the leaves. The verb "падать" is used to form such words (so called "сложные", which contain several words) as "водопад" (waterfall), камнепад (rockfall), снегопад (snowfall) and so on.

This is autumn fall of the leaves

It's used when it's when the leafs are falling down ;) When its КОСОПАД is when the hare is falling down :D (but I'm not sure about this in Russian) ЗВЕЗДОПАД - when the stars are falling down. (I'm not sure about this to..In the Bulgarian and in the Russian ЛИСТОПАД is the the same word and that's why I'm writing u this , but u should look for the others in the dictionary ;) ) http://www.wordreference.com/ . . . This is an amazing dictionary.It has the all words, no matter how strange they are and it's also doing a lot of other things ;) .It translates in Español | Français | Italiano | Deutsch | Português | Русский | Polski | Română | Čeština | Ελληνικά | Türkçe | 英汉词典 | 英和辞書 | 영-한 사전 | قاموس إنجليزي - عربي

it's like we know there are four seasons in the year and the action you were talking about it even in the autumn