Developers often rely on API documentation to learn API directives, i.e., constraints and guidelines related to API usage. Failing to follow API directives may cause defects or improper implementations. Since there are no industry-wide standards on how to document API directives, they take many forms and are often hard to understand by developers or challenging to parse with tools.

A domain glossary that organizes domain-specific concepts and their aliases and relations is essential for knowledge acquisition and software development. Existing approaches use linguistic heuristics or term-frequency-based statistics to identify domain specific terms from software documentation, and thus the accuracy is often low. In this paper, we propose a learning-based approach for automatic construction of domain glossary from source code and software documentation. The approach uses a set of high-quality seed terms identified from code identifiers and natural language concept definitions to train a domain-specific prediction model to recognize glossary terms based on the lexical and semantic context of the sentences mentioning domain-specific concepts. It then merges the aliases of the same concepts to their canonical names, selects a set of explanation sentences for each concept, and identifies "is a", "has a", and "related to" relations between the concepts. We apply our approach to deep learning domain and Hadoop domain and harvest 5,382 and 2,069 concepts together with 16,962 and 6,815 relations respectively. Our evaluation validates the accuracy of the extracted domain glossary and its usefulness for the fusion and acquisition of knowledge from different documents of different projects.