1. Let's throw a surprise party for Henry.

[What is the part of speech of 'surprise' in this sentence? A noun or an adjective?]

2. baseball field, baseball ground, baseball steadium, ballpark
[Are they all the same in meaning? Which ones are frequently used?]

In 1, "surprise" is being used as an adjective to describe "party."

In 2, yes, all the terms are similar, but watch the spelling -- "stadium"! I wouldn't use "baseball ground," though. Maybe others would, but I've never heard that before.

2. baseball field, baseball ground, baseball stadium, ballpark

[Okay. Thank you!]

Here's a slight difference for you.

On Sunday, my family and I are going to the baseball stadium in Houston. (The stadium includes the whole building that surrounds the actual field, in which there are the spectators' seats, the restaurants, the shops, etc.)

The Astros will be playing baseball on the field (the green grassy field with lines and bases on it) at Minute Maid Park: https://en.wikipedia.org/wiki/Minute_Maid_Park

Again, I've never heard anyone refer to a baseball ground.

1. To determine the part of speech of a word, you need to consider how it is functioning in the sentence. In the sentence "Let's throw a surprise party for Henry," the word 'surprise' is being used to describe the type of party. It is functioning as an adjective, modifying the noun 'party.' Therefore, in this sentence, 'surprise' is an adjective.

2. Although all the terms listed - baseball field, baseball ground, baseball stadium, ballpark - are related to the sport of baseball, they are not exactly the same in meaning. Here's a breakdown of their differences:

- Baseball field: This is a generic term that refers to any outdoor area or venue specifically designed or adapted for playing baseball. It can include various types of facilities, such as the playing surface, stands for spectators, and other relevant features.

- Baseball ground: This term is more commonly used in British English and is equivalent to the American English term "baseball field." They have the same meaning and refer to the same thing.

- Baseball stadium: A baseball stadium specifically refers to a large, organized venue or building used primarily for baseball games. It typically includes permanent seating areas, facilities like concession stands, and may have more advanced features like a scoreboard, luxury boxes, or training facilities.

- Ballpark: This is a more informal term that is often used as a synonym for baseball stadium. It generally signifies a location or venue where baseball games are played, but without the formal connotations of a dedicated stadium. It can also be used more broadly to refer to any place where baseball is played, including smaller or makeshift fields.

In terms of frequency of use, "baseball field" and "baseball stadium" are the most commonly used terms, especially in formal contexts. "Ballpark" is slightly less formal but still widely used, while "baseball ground" is primarily used in British English. The specific preference for usage may also vary depending on the region and context in which the terms are being used.