Certain terms in mathematics were created according to conventions that are not obvious to students who will use the term. When this is the case, investigating the choice of a name can reveal interesting and unforeseen connections among mathematical topics. In this study, we tasked prospective and practicing teachers to consider: What is geometric about geometric sequences? Participants embedded their answers to this question within a scripted dialogue between teacher- and student-characters in a mathematics classroom, provided commentary on this dialogue, and expanded on its mathematical content. In analyzing their submissions, we identified four different abductive arguments leveraged by participants to explain why geometric sequences are named as such. To analyze these informal arguments, we constructed and analyzed composite Toulmin models (Toulmin, 1958/2003) corresponding to each of the four arguments. We also compared the warrants and rebuttals that arose in response to each explanation and discuss the reappearance of similar rebuttals across arguments.