1. Compound words: This is the most likely meaning. A compound word is formed by combining two or more words, often with a hyphen or space between them (e.g., "high-speed," "check-in," "living room").
2. Words formed by combining morphemes: Morphemes are the smallest units of meaning in a language. Combining morphemes (prefixes, suffixes, roots) can create new words (e.g., "un-happy," "nation-al," "re-write").
3. Blends: A blend is a word created by merging parts of two words (e.g., "smog" from "smoke" and "fog").
4. Portmanteaus: This is a type of blend where the merging is more complete, creating a new word with its own meaning (e.g., "brunch" from "breakfast" and "lunch").
5. Combinations used in specific fields: In certain fields, like programming, "combining words" might refer to a specific process of joining text strings together.
Could you provide more context? What specifically are you asking about? Knowing the situation will help me give you a more precise answer.