to-and-fro

[too-uh n-froh] /ˈtu ənˈfroʊ/
adjective
1.
back-and-forth:
to-and-fro motion.
noun, plural to-and-fros.
2.
a continuous or regular movement backward and forward; an alternating movement, flux, flow, etc.:
the to-and-fro of the surf.
Origin
1820-30; adj. and noun use of adv. phrase to and fro, Middle English; see fro (def 2)

fro

[froh] /froʊ/
adverb
1.
Obsolete. from; back.
Idioms
2.
to and fro, alternating from one place to another; back and forth:
The trees were swaying to and fro in the wind.
Origin
1150-1200; Middle English frō, frā < Old Norse frā from; akin to Old English fram from
British Dictionary definitions for to and fro

to and fro

adjective, adverb
1.
back and forth
2.
here and there
Derived Forms
toing and froing, noun

fro1

/frəʊ/
adverb
1.
back or from See to and fro
Word Origin
C12: from Old Norse frā; related to Old English framfrom

fro2

/frəʊ/
noun (pl) fros, 'fros
1.
short for Afro
Word Origin and History for to and fro

fro

"away, backwards," c.1200, North English and Scottish dialectal fra, Midlands dialect fro, from Old Norse fra "from" (see from).

Idioms and Phrases with to and fro

to and fro

Back and forth, as in He was like a caged animal, pacing to and fro. Strictly speaking, to means “toward” and fro “away from,” but this idiom is used more vaguely in the sense of “moving alternately in different directions.” [ First half of 1300s ]

fro

see: to and fro