Principal English Translation: 

relating to one's childhood, a necessarily possessed form (see Karttunen); the element -pil- refers to something small (SW)

Orthographic Variants: 
Frances Karttunen: 

-PILTIYĀN necessarly possessed form one's childhood / mi niñez o el tiempo de mi niñez (R for first pers. sg. possessor) [(1)Rp.43]. This implies *PILTI 'to be a child.' R fails to mark the vowel of the final syllable long. See -PIL, -YĀN.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 196.