solitary
Being alone for a while, away from other people.
Solitary means alone, without others around. A solitary hiker walks the mountain trail by herself, seeing no one for hours. A solitary tree stands in the middle of an empty field, far from the forest. When you spend time in solitary contemplation, you're thinking deeply by yourself, without distractions or company.
The word implies real isolation or separateness that lasts for a meaningful period of time. A lighthouse keeper might live a solitary life, spending weeks alone on a rocky island. Some animals, like tigers, are solitary hunters who prefer to roam and hunt alone rather than in packs. In prison, solitary confinement means being kept completely alone in a cell, which is considered a severe punishment.
Solitary can describe people who naturally prefer being alone. A solitary person might choose to eat lunch by themselves, not because they're unfriendly, but because they genuinely enjoy their own company. This differs from lonely, which means feeling sad about being alone. You can be solitary and perfectly content, like a writer who needs quiet solitude to work, or a naturalist who spends solitary hours observing birds in the wilderness.