In soil, water that is readily available to plant roots is :

Soil water is categorized into three main types based on its availability to plants: gravitational, capillary, and hygroscopic water. Gravitational water occupies large soil pores after saturation but quickly drains away due to gravity, making it largely unavailable for sustained plant use. Hygroscopic water forms a microscopic film around soil particles and is held so tightly by adhesive forces that plant roots cannot extract it. Capillary water, however, is held in the soil's micropores by surface tension against the force of gravity. It is the primary source of moisture for plants because it is readily available for root absorption. This water is held between field capacity and the permanent wilting point, though its ease of extraction decreases as the soil dries [1]. Consequently, capillary water is the only form that is consistently and readily accessible to support plant growth.

Sources

1. [1] https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0003/531957/determining-readily-available-water-for-im.pdf