El amo: The master. Los amos: The masters.
El cuñado: The brother-in-law. Los cuñados: The brothers-in-law.
La cuñada: The sister-in-law. Las cuñadas: The sisters-in-law.
El yerno: The son-in-law. Los yernos: The sons-in-law.
La nuera: The daughter-in-law. Las nueras: The daughters-in-law.
El árbol: The tree. Los árboles: The trees.
El examen: The examination. Los exámenes: The examinations.
El lápiz: The pencil. Los lápices: The pencils.
El ómnibus: The omnibus. Los ómnibus: The omnibuses.
El jabalí: The boar. Los jabalíes: The boars.
3. Nouns ending in Y add =Es=, as—
El rey: The king. Los reyes: The kings.
La ley: The law. Las leyes: The laws.
4. The following add only =S= to form the plural—
Papá, Mamá, Bajá (a pasha), Sofá (sofa).[23]
[Footnote 23: Words ending in accented vowels are very few and the rule for those ending in á, ó, ú is not very strict.]
=Compound Nouns= form their plural according to sense, as—
Hijodalgo (a gentleman by birth), literally, "son of something"; Plu.,
Hijosdalgo (literally, "sons of something ").
Ferrocarril (railway), literally, "iron railroad"; Plu., Ferrocarriles
(literally, "iron railroads").
Such nouns are rare.[24]
[Footnote 24: A verb as a component part does not change, as El portabandera (the standard-bearer), Los portabanderas (the standard-bearers).]