u, f., in Norse MSS. spelt afusa, Dipl. i. 3; avusa, Str. 27, 54, Sks. 775 B; afuusa, N. G. L. i. 446. In Icel. always spelt with au, av, or ö, by changing the vowel, öfusa, aufusa, Ó. H. 155, where, however, some MSS. have aufussa, avfusa, Fms. viii. 39, 250; öfusa, Fs. 123; ofusa, 677. 3, Band. 6; öfussa, Bs. i. 481: the change of vowel is caused by the following f (v). The word is now quite obsolete, and its etymology is somewhat uncertain; it may be qs. á-fúss, or af-fúss, an ‘af-’ intens. and ‘fúss,’ willing, this last suggestion would best suit the Norse form. Its sense is thanks, gratitude, satisfaction, pleasure, and is almost exclusively used either as a supplement to ‘þökk’ or in such phrases as, kunna e-m au., or e-m er au. á e-u, to be pleased, gratified with; þakka með mikilli a., to thank heartily, Str. 27; ef yðr er þar nokkur a. á, if it be any pleasure to you, Fms. ix. 495; kunna e-m au. e-s, or with ‘at,’ to be thankful, Fb. ii. 257, Eg. 111, Ó. H. 56, Fms. viii. 1. c., Bs. i. 481, H. E. i. 432, Eg. 522, Sturl. iii. 125, Fær. 209, 677. 3; leggja at móti þökk ok au., Ó. H. 155; viljum vér au. gefa þeim góðum mönnum, we will thank them, Fms. viii. 250; var mönnum mikil ö. á því, much pleased by it, Fs. 123; hafa í móti þökk ok ö., Band. 19 new Ed.

COMPDS: aufusugestr, aufusuorð, aufvisusvipr.