The Collaborative International Dictionary of English v.0.48:
Persevere \Per`se*vere"\, v. i. [imp. & p. p. Persevered; p.
pr. & vb. n. Persevering.] [F. pers['e]v['e]rer, L.
perseverare, fr. perseverus very strict; per + severus
strict, severe. See Per-, and Severe.]
To persist in any business or enterprise undertaken; to
pursue steadily any project or course begun; to maintain a
purpose in spite of counter influences, opposition, or
discouragement; not to give or abandon what is undertaken.
Thrice happy, if they know
Their happiness, and persevere upright. --Milton.
Syn: To Persevere, Continue, Persist.
Usage: The idea of not laying aside is common to these words.
Continue is the generic term, denoting simply to do as
one has done hitherto. To persevere is to continue in
a given course in spite of discouragements, etc., from
a desire to obtain our end. To persist is to continue
from a determination of will not to give up. Persist
is frequently used in a bad sense, implying obstinacy
in pursuing an unworthy aim.