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Why is coconut oil semiliquid even though it contains many saturated fatty acids?

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A composite diagram shows the structural formulas, space-filling models, and simplified depictions of lipid molecules including stearic acid and phosphatidylcholine, and how these assemble into a micelle and lipid bilayer, with labels identifying hydrophilic heads and hydrophobic tails. — Lipid Structure and properties of two representative lipids. Both stearic acid (a fatty acid) and phosphatidylcholine (a phospholipid) are composed of chemical groups that form polar “heads” and nonpolar “tails.” The polar heads are hydrophilic, or soluble in water, whereas the nonpolar tails are hydrophobic, or insoluble in water. Lipid molecules of this composition spontaneously form aggregate structures such as micelles and lipid bilayers, with their hydrophilic ends oriented toward the watery medium and their hydrophobic ends shielded from the water.

Coconut oil is a yellowish-white solid or semiliquid at room temperature because it has a relatively low melting point of 23 °C (74 °F). While it is true that coconut oil is composed of up to 90 percent saturated fat, its physical state is determined by the specific types of fatty acids it contains.1

The primary component of coconut oil is lauric acid, a 12-carbon saturated fatty acid that makes up 45–50 percent of its composition. Compared to the longer-chain saturated fatty acids found in many other animal and vegetable fats—such as 16-carbon palmitic acid or 18-carbon stearic acid—lauric acid has a shorter carbon chain. These shorter chains result in weaker intermolecular forces, which lowers the melting point of the oil compared to fats dominated by longer-chain saturated fatty acids. Consequently, coconut oil remains in a semiliquid or soft solid state at typical room temperatures.12