The idiom "like night day" is a comparison between two things that are so different as to be almost opposite. In terms of pronunciation, "like" is pronounced /laɪk/ with the diphthong /aɪ/ and the voiceless velar fricative /k/. "Night" is pronounced /naɪt/ with the same diphthong as "like" but a different final consonant, the voiceless dental fricative /θ/. "Day" is pronounced /deɪ/ with the diphthong /eɪ/ and the voiced alveolar stop /d/.
"Like night and day" is an idiomatic phrase used to describe two things or situations that are fundamentally different or diametrically opposite from each other. The phrase suggests a stark contrast between two elements, just as the characteristics of night and day are distinct and contradictory.
The expression often emphasizes the extreme differences between two phenomena. In a literal sense, night and day are completely dissimilar periods of time, with night symbolizing darkness, stillness, and rest, while day represents brightness, activity, and wakefulness. Similarly, when used metaphorically, "like night and day" conveys a striking dissimilarity that is immediately evident.
This phrase can be employed to illustrate opposite personalities, contradictory viewpoints, or drastic changes over time. For example, one might say that the behavior of two siblings can be like night and day if one is introverted and studious while the other is outgoing and carefree. Additionally, the saying can be used to describe significant transformations, such as a neighborhood that has transformed from a quiet residential area to a bustling commercial district, altering its ambiance completely.
Overall, the phrase "like night and day" encapsulates the concept of complete and total contrast, making it an effective way to emphasize the vast differences between two things or situations.