a. The Gerund is a verbal noun, corresponding in meaning to the English verbal noun in -ing (§ 502): as, loquendí causá, for the sake of speaking.
NOTE: The Gerund is found only in the oblique cases. A corresponding nominative is supplied by the Infinitive: thus, scríbere est útile, writing (to write) is useful; but, ars scríbendí, the art of writing.
b. The Supine is in form a noun of the fourth declension (§ 94. b), found only in the accusative ending in -tum, -sum, and the dative or ablative ending in -tú, -sú.
The Supine in -um is used after verbs and the Supine in -ú after adjectives (§§ 509, 510): -