12 The precise meaning of the expression "the severity of a term of imprisonment increases exponentially as it increases in length" does not appear to have been previously explained in any detail. According to the Shorter Oxford Dictionary, the term "exponential" is related to mathematics, being something which involves "the unknown quantity or valuation of an exponent, i.e. a symbol denoting the power of an index" such as: 62 or 6 to the power of 2. This is known as an exponential quality or function. A similar meaning is given in the Oxford Illustrated Dictionary as involving the "unknown quantity or valuation of an exponent, i.e. a symbol denoting the power of an index." A similar mathematical meaning is given in the Macquarie Dictionary. The colloquial meaning is also given, namely, something that is "marked by a rapid increase in magnitude, number, etcetera". In my opinion, the term was not used by Ipp J in any technical or mathematical sense, but to suggest that the increase in length of a sentence is perceived as increasingly greater severity than the actual length of the sentence. Thus, for example, the doubling of a sentence may be perceived as being more than twice as severe, in the sense that the severity is compounding by a factor more than simply the additional length of the sentence. As Ipp J himself said in Jarvis at 207, immediately following the proposition in question: