The verb "lean" is a versatile verb in English, commonly used to describe the action of inclining or resting against something. It is generally considered a regular verb in English, following the typical pattern for regular verb conjugation. However, it can also have irregular forms, particularly in British English.

In the present simple tense, "lean" follows its base form for most subjects: "I lean," "you lean," "he/she/it leans," and so on. For example, "He leans against the wall when he's tired."

In the past simple tense, "lean" can change to either "leaned" (regular) or "leant" (irregular, more common in British English). This form is used to describe the action of inclining or resting against something in the past. For instance, "She leaned/leant out of the window to get a better view."

The past participle of "lean" can also be "leaned" or "leant." When forming perfect tenses, such as the present perfect or past perfect, the past participle is combined with auxiliary verbs. An example sentence is "They have leaned/leant on each other for support during tough times."

"Lean" can be used both transitively and intransitively. As a transitive verb, it means to incline or cause to rest against something: "He leaned the ladder against the wall." As an intransitive verb, it means to incline or rest: "She leans to the left when she walks."

The verb "lean" is also used in various idiomatic expressions, such as "lean on" (to rely on someone for support), "lean into" (to embrace or accept something fully), and "lean towards" (to have a tendency or preference for something).

Understanding the conjugation and usage of "lean" is important for accurately describing actions related to inclining, resting, or relying on something or someone. Its versatility in both regular and irregular forms adds to its richness in the English language.