The general rule is that the plural of *x is *xes, and conversely the singular of *xes is *x Notable exceptions being axis=>axes, index => indeces, vertex=>vertices, ox=>oxen. 
The general rule is that the plural of *x is *xes, and conversely the singular of *xes is *x Notable exceptions being axis=>axes, index => indeces, vertex=>vertices, ox=>oxen. 

"Even more confusingly, one word may be the plural form of two different singular words. So /bases/ means more than one of both /base/ and /basis/, and /ellipses/ can refer to both /ellipse/ and /ellipsis/. The winner in this category is /axes/, which is the plural of /ax, axe/ and /axis/." 

(Richard Watson Todd, /Much Ado About English: Up and Down the Bizarre Byways of a Fascinating Language/. Nicholas Brealey, 2006) 

nooku/nooku-platform,timble/kodekit-platform,nooku/nooku-platform,nooku/nooku-platform,timble/kodekit-platform,timble/kodekit-platform,nooku/nooku-platform,nooku/nooku-platform,timble/kodekit-platform,timble/kodekit-platform