Emily Dickinson Lexicon

OB'STI-N-A-CY, n. [L. obstinatio, from obsto, to stand against, to oppose; ob and sto.]

1. A fixedness in opinion or resolution that can not be shaken at all, or not without great difficulty; firm and usually unreasonable adherence to an opinion, purpose or system; a fixedness that will not yield to persuasion, arguments or other means. Obstinacy may not always convey the idea of unreasonable or unjustifiable firmness; as, when we say, soldiers fight with obstinacy. But often, and perhaps usually, the word denotes a fixedness of resolution which is not to be vindicated under the circumstances; stubbornness; pertinacity; persistency.
2. Fixedness that will not yield to application, or that yields with difficulty; as, the obstinacy of a disease or evil.