1. To extend a long way down from the surface. English = (be) deep.
2. Of thoughts, ideas, etc., to be serious and to be about important things. English = (be) deep, (be) profound.
3. Of understand or analysis, to be very serious, exhaustive, or complete, and to show a great deal of intellectual understanding. English = (be) deep, (be) profound.
4. Used to describe communication and information which includes all of the details and facts that are relevant to the topic. English = (be) detailed, (be) comprehensive.