Topic Sentence Definition. Topic sentences are special sentences that serve as guideposts to the writer and reader; they help shape the essay and move it along from idea to idea. If you have already gathered information and developed some support for a thesis, you may find that your support falls into groups or categories. A rule of thumb is that you can develop a topic sentence for each category to help shape that information and to cue your reading audience in to a change in supporting idea.
The definition of a counterclaim is a claim made to rebut accusations against you. If you are sued for breaching a contract and you, in turn, also file suit against the plaintiff and claim thathe was really the one who breached the contract, your claim against the original plaintiff is an example of a counterclaim.
Countertrade is a means to help countries with trade imbalances trade by means other than the use of hard currency. It's often used when the foreign currency of the potential exporter is in short supply in the foreign country or when the country has imposed limitations on the use of foreign currency for imports.