mal-

mal- flips a root to its exact contrary, and it is the single biggest reason Esperanto vocabulary is smaller than it looks. Learn granda, varma, fermi and juna and you have also learned malgranda, malvarma, malfermi and maljuna for nothing. The prefix changes no grammar: whatever ending the root carried, the opposite keeps it, so an adjective stays an adjective and a verb stays a verb.

The trap is that mal- means opposite, not negative. ne denies a statement, sen- marks absence, and mal- names the far end of a scale, so malbona is bad rather than not good. Beware the one common look-alike: malgraŭ (in spite of) is a single word, not mal- plus anything. By contrast malantaŭ (behind), maldekstra (left) and malsupre (below) are genuine mal- words, the opposites of antaŭ, dekstra and supre.