Originally 蹤. 足 is foot and 從 is follow (modern Japanese 従). The latter lends its sound and possibly its meaning. Thus, something like follow (traces of) of someones feet: ‘footprints, traces, tracks’. In traditional Chinese 蹤 is still being used, but Japanese uses the more recent variant 踪 which uses 宗. (This variant may have restored the phonetic - the pronunciation of 宗 is in Mandarin Chinese still identical to that of 踪.) Suggest taking 宗 as sect.
Mnemonic: followed a sect, got cold feet and went missing
Looking at episode four of 絶対零度 zettai reido I stumbled on the word 失踪.
Shissousha wa, jikensei ga hikukeraba taishita sousa dekinai kara na
We can’t do a proper search for the missing person if there is little information to go on.
shissou touji, yonjuu issai deshita.
When he went missing, he was 41 years old.
Earlier, in other police series, I had learned (and have heard several times since) 行方不明 yukue fumei, and in fact, the scene starts with a box that is addressed to: 警視庁 行方不明者捜索担当 keishichou yukuefumeisha sousaku tantou (for the police department in charge of finding missing persons). But I had not heard shissou 失踪 ‘disappearance’ earlier. ¹ More to the point for this scribble, I’d never seen the character 踪 - which is used to write the ending of the word.
As it happens, 踪 is one of those characters that is used to help write only one word or expression. If you’d never encounter this particular word for ‘missing’, you could forget about 踪. However, according to a general Google search, you’re just as likely to come across 失踪者 as 行方不明者 (note however, that a search restricted to Asahi Shimbun gave me more than twice as much hits for 行方不明者; also, 行方不明 is more frequent in expressions like 行方不明になった).
With 踪 being a 表外字 (hyougaiji, a character that is not on the lists of characters that every Japanese learns in school) you’d expect that hiragana spelling might be common. Even Wikipedia suggests as much.² However, when I searched Ashahi Shimbun for 失そう I got only three hits, while for 失踪 I got 842 (though in at least one article it had it’s pronunciation attached to it). It seems 踪 is definitely a need-to-know character.
The phonetic of 踪 sou is 宗 shuu, so, not a perfect match. However, with 宗 being very frequent, it at least hints at the initial s.
According to the Unihan dictionary, 踪 has the basic meaning of ‘footprints, traces, tracks’ (Wieger says ‘a footstep; a trace’). Since 踪 has 足 foot as signific and 宗 seems to do nothing more than lend its sound (which by the way in Chinese is still a perfect match for 踪) that would seem to be the end of it. Henshall often tries to find some semantic relevance of the phonetic as well, but there seems to be none. But wait! It turns out that 踪 is a fairly modern combination. That may in fact be the reason (just guessing) that the phonetic still works in Chinese. The original Chinese word or morpheme used to be written with 蹤, having 從 (modern Japanese 従) as phonetic. While the sound of 從 is not a match for 蹤 (in Mandarin at least) it is still the spelling used in traditional Chinese.
The word with which 從/従 was written used the have meanings like ‘go along with; follow’, and in fact Japanese still uses 従 with words that cover those meanings (追従する人 tuijuusuru hito ‘a person who follows or serves another’ or even kun’yomi 従って shitagatte, ‘from this follows’). And I’d say that for a word with meanings like ‘footprints, traces, tracks’, ‘following’ certainly has semantic relevance! But of course Japanese uses that (probably more modern) variant 踪 - even though in Japanese 宗 is almost just as unhelpful as phonetic as 從 is (on the other hand, 宗 is easier to write).