Clipping of 中折れ帽子 (nakaorebōshi, “fedora”) (felt hat)

a fedora (felt hat)

the Mesolithic

small mercy (from some misfortune); silver lining of a dark cloud; consolation in sadness; blessing in disguise

(mathematics) geometric mean, specifically, if the variables a, b, c satisfy the relation a:b=b:c, then b is the 幾何中項 of a and c.

a metatarsal bone

the Second Sino-Japanese War

Kyūjitai form of 営業中 (“open”)

(mathematics) geometrical

"Historical kana usage", a prescriptive method of using kana to write Japanese. Devised in the Edo period by Keichū (契沖) and taught in schools until 1946, it aims to be etymologically faithful and reflects earlier stages of the language (Heian period and earlier).