armor, high (voice), A grade, first class, former, instep, carapace
甲 centers on a hard outer covering or top position: armor, a shell, the instep, or the first/highest rank. The 'high voice' and 'former' senses are less central but relate to being top or first.
甲 is a pictograph of a hard outer covering, such as a seed shell or armor plate, with the vertical stroke representing the seam or ridge. The modern form retains this basic shape.
Picture a hard shell with a ridge running down the middle: 甲 is armor, a carapace, or the top of the foot. It also represents the first rank, like the top of a class.
For コウ, imagine a coat of armor: coat -> コウ, and the hard shell protects the warrior.
result (that makes an act worthwhile); worth (in doing something); value; effect; use; benefit; avail
carapace; shell
Koshien Stadium (baseball park in Nishinomiya, Hyōgo Prefecture)
armoring; armouring; armor; armour
Kōfu (city in Yamanashi)
thyroid (gland)
value in doing something; feeling that something is worth doing; rewarding feeling; sense of satisfaction
deck (of a ship)
rhinoceros beetle (esp. the Japanese rhinoceros beetle, Trypoxylus dichotomus)
shell (of a crab, tortoise, etc.); carapace; plastron
armor and helmet
armoured vehicle; armored vehicle
tortoiseshell; tortoise shell
back of the hand
carapace; shell; crust
armour (e.g. tank); armor
beetle
A-grade; first-class
high-pitched; shrill
first and second; A and B