From regard + -ful.
regardful (comparative more regardful, superlative most regardful)
- Respectful. [from 16th c.]
1603, Michel de Montaigne, chapter 8, in John Florio, transl., The Essayes, […], book II, printed at London: By Val[entine] Simmes for Edward Blount […], OCLC 946730821:
I […] take care for the general, to have a regardfull respect of that which you leave behind you.
- (now rare) Watchful, observant. [from 16th c.]
- 1596, Edmund Spenser, The Faerie Queene, IV.7:
- And evermore, when with regardfull sight / She looking backe espies that griesly wight / Approching nigh, she gins to mend her pace […].