Knag n. : A knot in wood; a protuberance.

Knag n. : A wooden peg for hanging things on.

Knag n. : The prong of an antler.

Knag n. : The rugged top of a hill.

Example:
Anyone who's read Sophie's World please help?!?

Taxonomy
knag, Inflection, Wiktionary, past participle, present participle, Scottish English, English, Pronunciation, spellings, Danish, free dictionary, search, Synonyms, Rhymes, peg, Infinitive, Third person singular, third-person.

Defination from the web:
knag (plural knags) A short spur or stiff projection from the trunk or branch of a tree, such as the stunted dead branch of a fir ... to knag (third-person singular simple present knags, present participle knagging, simple past and past participle knagged) To hang something on a peg ...