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Phrase(s): *from scratch
Fig. [making something] by starting from the beginning with the basic ingredients. (*Typically: bake something ~; do something ~; make something ~; start (something) ~.) • We made the cake from scratch, using no prepared ingredients. • I didn’t have a ladder, so I made one from scratch.
McGrawhill's American Idioms And Phrasal Verbs
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From the very beginning, from the outset; from nothing. For example, I knew we'd have a problem from scratch. Similarly, to start from scratch means "to start from the very beginning," as in After the business failed, they decided to reorganize and start from scratch. This term comes from racing, where a competitor starts from the line scratched into the ground (whereas others may start ahead with a handicap). [Mid-1800s] Also see FROM THE GROUND UP; FROM THE WORD GO.
American Heritage Idioms