1. Bottomless or fathomless.

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

• abysmall,
• abyssmal,
• absymal,
• abissmal,
• abismall,
• abdomal,
• obismal,
• anysmall,
• abbysmal,
• abymal,
• abnomal,
• abismal,
• abismol,
• abysal,
• abusal,
• abysmil,
• abbysal,
• abysmaly,
• anerysmal,
• anosmai

• abashment,
• abasement,
• absently,
• abysmally,
• abysm.

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

The plural form of the word "abysmal" is "abysmals".

The singular form of the word "abysmal" is "abyss"