Colloquial describes language used in familiar and informal conversation. It's often paired with words like "term" or "expression." An author might adopt a colloquial style depending on her audience. The American woodcock, for instance, has many colloquial names such as "timberdoodle" and "bogsucker." These names are informal ways of referring to the bird. The word "colloquial" derives from "colloquy," meaning a conversation. Both words trace back to the Latin "colloquī," to converse. Initially, "colloquial" simply meant related to conversation. Its meaning evolved to specifically denote language suitable for informal talk. Later, it gained a secondary meaning for language inappropriately informal for a situation. For example, describing Ernest Shackleton's crew as "in quite a pickle" would be too colloquial for an academic paper. The word "pickle," though meaning a difficult situation, is unacceptably informal in that context.