Þroskast

As defined by A Concise Dictionary of Old Icelandic (Geir Zoëga):

þroskast

(að), v. refl. to grow up to full age, live to be a man.

Possible runic inscription in Younger Futhark:ᚦᚱᚢᛋᚴᛅᛋᛏ

Also available in related dictionaries:

This headword also appears in dictionaries of other languages closely related to Old Icelandic.

• Old Norwegian - Johan Fritzner's Dictionary