from The American Heritage® Dictionary of the English Language, 4th Edition
- interj. Used to express mild surprise or delight.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- interj. A mild expression of surprise or enthusiasm as to be put in place of “God”, particularly in fear of saying the Lord’s name in vain.
from The Century Dictionary and Cyclopedia
- A minced oath, commonly in the phrase by gosh.
Alteration of God.(American Heritage® Dictionary of the English Language, Fourth Edition)
Euphemism (or minced oath) for god. First seen in 1757 as by gosh, probably from by gosse in Udall's Ralph Roister Doister (c. 1553) (Wiktionary)