Attributive adjectives, adjectives placed before the noun, are declined like this:
"kald" is for feminine and masculine indefinite singulars.
"kaldt" goes with neuter indefinite singulars, and is also the adverb.
"kalde" is for plurals and definite singulars of all genders.
For predicative adjectives, adjectives positioned after the noun, the rules differ slightly. The gender specific forms are used not only with indefinite singular nouns, but with the definite singular ones as well, as illustrated in the sentence up top.
"kalt" is a verb form.