～しい (adjective suffix)

• Reading: しい
• Romaji: shii
• Formation: Adjective stem + しい

Meaning

An infix attached to the stem of certain い-adjectives to indicate a quality that one can perceive, feel, or sense subjectively. It often conveys emotional or sensory impressions.

The しい ending appears in a large class of い-adjectives that express subjective feelings, emotional states, or qualities perceived through personal experience. Adjectives ending in しい tend to describe internal states (悲しい, 嬉しい, 寂しい) or impressions formed through sensory evaluation (美しい, 怪しい, 親しい). Unlike plain い-adjectives that often describe objective properties (大きい, 高い), しい-adjectives carry a more evaluative or emotional nuance. Historically, しい derives from an Old Japanese adjectival suffix that indicated something worthy of a particular feeling. Recognising the しい pattern helps learners anticipate meaning and conjugation: these adjectives conjugate exactly like other い-adjectives (しくない, しかった, しくて).

Examples

1. この景色は本当に美しい。 This scenery is truly beautiful.
2. 試験に受かって嬉しい。 I'm happy that I passed the exam.
3. 一人暮らしは時々寂しい。 Living alone is sometimes lonely.

Usage Guide

Context: spoken, written, everyday

Tone: emotive

Do Say

• 彼女の歌声は美しいですね。
• 久しぶりに友達に会えて嬉しかった。
• この話は本当に悲しい。
• 夜道は暗くて恐ろしい。

Don't Say

• 大きしい建物ですね。(大きい does not take しい — it is already a complete い-adjective) → 大きい建物ですね。
• この料理は美しいです。(美しい describes visual beauty, not taste — use 美味しい for delicious) → この料理は美味しいです。

Origin & History

Derived from the Old Japanese suffix しい, which was used to form adjectives expressing subjective evaluation. It traces back to the classical form しき/しけれ and has been productive in creating emotive adjectives throughout Japanese history.

Cultural Context

Generation: All ages

Social background: Universal