• lastr,
• casre,
• costto,
• cantre,
• astry,
• tastry,
• fastr,
• eastre,
• casta,
• castr,
• fastre,
• destro,
• costr,
• castom,
• castros,
• casere,
• coastr,
• mastreo,
• custo,
• casrd

• Castorena,
• castroism,
• Cast iron,
• castries,
• cistron,
• castrated,
• castor,
• castrato,
• castruita,
• castrate,
• caster,
• castrillo,
• Castrejon,
• cast-iron.

The adjective form of the word "castro" is "castrense".

The plural form of "castro" is "castros".

The singular form of the word "castro" is "castro". It is already in singular form.