A pair of words that differ from each other only by one sound: e.g. drug / drum. These two words have different meanings only because of the single difference in sound between them: /g/ vs. /m/. These two sounds are therefore phonemes of English.
two words sounding alike in all but one feature, e.g., "heating/hitting": in this case the feature is the first vowel.
Two very similar words often used for discrimination practice. One word of the pair is the example word and contains the new phonetic element; the other word is the contrast word and contains familiar letter(s) which substitute for the new phonetic element. Examples: beat/seat, feet/meet/, stop/mop.