adj. aged, having lived long, (lit.) year-full
iphantadj. aged, having lived long, old (with no connotation of weakness)
iphant (long-lived, litearally ”year-full”), pl. iphaint. The spelling used in the source is ”ifant” (LR:400 s.v. YEN), but since the f arises from earlier (n > m +) p via nasal mutation, it should be written ph according to the spelling conventions described in LotR Appendix E.