Þróast

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

þróast

(að), v. refl. to wax, increase, grow; metnaðr honum ~, pride waxes in him.

Possible runic inscription in Younger Futhark:ᚦᚱᚢᛅᛋᛏ

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