ˈkɑː.dɪ.nəl ˈkɑɹdɪnəl ˈsɛntɹəl ˈsɛntɹəl ˌfʌndəˈmɛntəl ˈpɹaɪməl in or near a center or constituting a center; the inner area a central position serving as an essential component a cardinal rule the central cause of the problem an example that was fundamental to the argument computers are fundamental to modern industrial structure a workplace that serves as a telecommunications facility where lines from telephones can be connected together to permit communication