Old English deoplice "at or to a great depth," used in both literal and figurative senses; see deep (adj.) + -ly (2). Meaning "profoundly, thoroughly" is from c. 1200; that of "with strong feeling, passionately" from c. 1400. Of sighing from 1550s; of drinking from 1690s.
They felt the loss deeply
dived deeply
de-emphasize
deep
deep six
deepen
deep-freeze
deeply
deepness
deep-sea
deep-seated
deep-set
deer