Definition of blot one's copybook
- The star football player blotted his copybook by using bad language in an interview.
: a soiling or disfiguring mark : spot
: a mark of reproach : moral flaw
: a usually nitrocellulose or nylon sheet that contains spots of immobilized macromolecules (as of DNA, RNA, or protein) or their fragments and is used to identify specific components of the spots by applying a molecular probe (such as a complementary nucleic acid or a radiolabeled antibody) — compare southern blot, western blot
: to spot, stain, or spatter with a discoloring substance
: to dry (something, such as writing) with an absorbing agent
: a lone backgammon man exposed to capture
: a weak or exposed point
: a book formerly used in teaching penmanship and containing models for imitation
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