1. That may be communicated by contact, or by a subtile excreted matter; poisonous; pestilential; containing mischief that may be propagated; affecting others. Contagious Diseases Acts, Acts to prevent the spread of certain contagions diseases.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• contageous,
• catagious,
• contagouse,
• contegeous,
• contunious,
• cotagious,
• contaigous,
• contagios,
• contageious,
• contagiuos,
• contagis,
• contajous,
• contingious,
• contnious,
• contagiouse,
• contcious,
• contigious,
• continious,
• contajious,
• conatgious

• contiguous,
• contiguity,
• commodious,
• contagiously,
• contuse,
• contacting,
• contusion,
• contagion,
• contagions,
• contestant,
• contestation.

The adjective form of the word "contagious" is "contagious".

The plural form of "contagious" is also "contagious." The word does not change in plural form.

The singular form of the word "contagious" is "contagion"