The word 渗入 is formed by combining the character 渗, meaning 'to seep' or 'permeate,' which includes the water radical (氵) to signify liquid-related action, with the character 入, meaning 'to enter.' This combination creates a compound verb where 渗 conveys the action of seeping and 入 directs that action inward, resulting in the meaning 'to seep into' or 'infiltrate.'