Indoor/ˈɪndɔːr/ Definition 1 of 3Pro Tip 1/3Environment Specific Use 'indoor' to specify activities or things meant for enclosed spaces. She bought an indoor grill for her apartment. Pro Tip 2/3Weather Independent 'Indoor' implies activities or uses that are not affected by outdoor weather. Indoor gyms are great for rainy days. Pro Tip 3/3Contrast with Outdoor Contrasting 'indoor' with 'outdoor' can clarify the setting of an activity or item. She prefers indoor dining to outdoor patios.