‘吝于’ is a two-character phrase meaning 'reluctant to' or 'stingy in doing something.' It expresses hesitation, unwillingness, or excessive caution—especially regarding giving, sharing, or acting. The character 吝 (lìn) originally meant 'stingy' or 'grudging,' while 于 (yú) is a preposition indicating the domain or action involved (e.g., 'in [doing] X'). Together, 吝于 functions as a fixed collocation that must be followed by a verb or verbal phrase (e.g., 吝于表达, 吝于帮助). It carries a slightly formal or literary tone and is often used in written Chinese or thoughtful speech.

This phrase emphasizes emotional restraint rather than mere scarcity—it’s about psychological resistance, not lack of resources. It frequently appears in contexts discussing communication, generosity, self-expression, or effort. Unlike standalone adjectives, 吝于 cannot stand alone; it always governs an infinitive-like verbal complement. Its negative connotation suggests a perceived shortcoming—someone who is emotionally closed-off or overly cautious in offering support, praise, or time.