noun
D size battery
Refers specifically to the D-size dry cell battery, commonly used in flashlights and portable radios.
この懐中電灯は単１形の電池を使います。
This flashlight uses D size batteries.
noun which may take the genitive case particle 'no'
monomorphic
Technical term in biology or chemistry meaning having a single form or structure; not commonly used in everyday conversation.
この種は単一形の葉を持つ。
This species has monomorphic leaves.
Compound of 単 (single) + 一 (one) + 形 (type/form). The battery sense derives from the standardized naming of dry cell sizes in Japan.