Onset-Rime
Onset and Rime are technical terms used to describe phonological units of a spoken syllable. A syllable can normally be divided into two parts: the onset, which consists of the initial consonant or consonant blend, and the rime which consissts of the vowel and any final consonants. So in the word "strap", "str" is the onset and "ap" is the rime. Words which share the same rime will also rhyme, but the spelling will be constant and not vary as it does with rhyme.