Other forms: communicably
A cold is a communicable disease, i.e. it's contagious, so you can pass it on to others. If you are a politician, your basic message should be communicable or communicated easily to others.
Whether a cold or a message, think of transmitting something when using the word communicable. In this word, you might see communicate, commune, and community. All of these words come from the Latin root communicare which means "to share." When something is communicable it is easily shared with a community of people.