adj.难以定义的，无法解释的
n.难以下定义的事物

The concept of infinity is truly indefinable in everyday language.
无限的概念在日常语言中是无法精确定义的。
Love can be an indefinable feeling that words fail to capture completely.
爱可能是一种无法用言语完全捕捉到的模糊情感。
The beauty of a sunset is an indefinable experience, unique to each observer.
日落的美是一个无法言表的经历，对每个人来说都是独一无二的。
Art, in its truest form, is often indefinable and open to individual interpretation.
艺术的真谛常常是无法定义的，各人解读各异。
Happiness can be an indefinable state, difficult to describe but instantly recognizable.
幸福可能是一种难以描述但又立刻能被认出的模糊状态。
The complexity of human nature makes it an ever-indefinable subject for philosophers.
人性的复杂性使其成为哲学家们永远无法完全定义的主题。
The taste of a perfectly ripe fruit is an indefinable delight.
完美成熟的水果的味道是一种无法言喻的愉悦。
The boundaries between different genres of music are often indefinable.
不同音乐类型的界限常常是模糊不清的。
The concept of time is both tangible and indefinable, eluding precise definition.
时间的概念既具体又难以定义，难以给出精确的界定。
True friendship is an indefinable bond that transcends words and actions.
真正的友谊是一种超越言语和行动的无法言表的纽带。