1. To sap; to excavate the earth beneath; to remove the foundation or support of anything by clandestine means.

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

• undemines,
• undering,
• underging,
• underminng,
• undercone,
• undefine,
• underoing,
• undeline,
• underming,
• undetermine,
• unfemine,
• underone,
• toundermine,
• undermone,
• undermne,
• undremine,
• undermnie,
• undermien,
• undermyne,
• underunk

• underneath,
• underived,
• undersurface,
• underwriter,
• underrating,
• undersea,
• under arms,
• underfelt,
• undertaker,
• underfur,
• undertake,
• underseller,
• unadorned,
• underhung,
• undertide,
• untier,
• underprice,
• undergarment,
• undersell,
• underbelly,
• underpin,
• underling,
• underwater,
• underlie,
• underdress,
• underseal,
• undercurrent,
• underworld,
• underscore,
• undertaking,
• undersize,
• undermanned,
• underwrite,
• understate,
• undersign,
• underdone,
• underlying,
• underdown,
• underframe,
• undersealed,
• undoer,
• underside,
• underexpose,
• underweight,
• undergo,
• underperform,
• under wraps,
• underarm,
• undervalue,
• undercover,
• underwing,
• underskirt,
• undersized,
• underspent,
• underwear,
• undershrub,
• underfed,
• underage,
• underline,
• underpart,
• underbred,
• underrate,
• underhand,
• underpants,
• underhanded,
• undersoil,
• undertone,
• untermeyer,
• under fire,
• undershirt,
• undersexed,
• underspend,
• undergird,
• underquote.

The adverb for the word "undermine" is "underminingly".

The adjective form of the word "undermine" is "undermining".

The plural form of "undermine" is "undermines"

The singular form of the word "undermine" is "undermine". The word does not change its form in the singular.