〜っぽい

Noun + っぽい (子どもっぽい, 白っぽい, 熱っぽい). Verb ます-stem + っぽい, with only a few verbs such as 忘れる, 怒る, 飽きる (忘れっぽい, 怒りっぽい, 飽きっぽい). い-adjective without the last い + っぽい, with a few words such as 安い (安っぽい). The new word changes like an い-adjective: っぽい + noun (白っぽいかばん), っぽくない (negative), っぽかった (past), っぽく + verb (安っぽく見える, 忘れっぽくなる).

• このスープは少し水っぽいですね。

  このスープはすこしみずっぽいですね。

  This soup is a little watery, isn't it?

• 兄はもう25歳なのに、考え方が子どもっぽい。

  あにはもうにじゅうごさいなのに、かんがえかたがこどもっぽい。

  My older brother is already 25, but his way of thinking is childish.

• 妹は中学生ですが、大人っぽい服が好きです。

  いもうとはちゅうがくせいですが、おとなっぽいふくがすきです。

  My younger sister is a junior high school student, but she likes clothes that look grown-up.

• 朝は熱っぽかったですが、今はもう大丈夫です。

  あさはねつっぽかったですが、いまはもうだいじょうぶです。

  I felt a little feverish this morning, but I'm fine now.

• その白っぽいかばんは、リンさんのですか。

  そのしろっぽいかばんは、リンさんのですか。

  Is that whitish bag yours, Linh?

• 高い服なのに、ちょっと安っぽく見えない？

  たかいふくなのに、ちょっとやすっぽくみえない？

  These clothes are expensive, but don't they look a little cheap?

• 父は怒りっぽくないけど、一度怒るととても怖い。

  ちちはおこりっぽくないけど、いちどおこるととてもこわい。

  My father doesn't get angry easily, but once he gets angry, he is very scary.

• Using っぽい as praise for someone who really is that noun. For a real child who acts in a sweet, natural way: ✕ 5歳の息子は子どもっぽくてかわいい → ○ 5歳の息子は子どもらしくてかわいい. 子どもっぽい is usually said about an adult who acts like a child.
• Putting the dictionary form or the full い-adjective before っぽい. To say that a person tends to forget, use the ます-stem: ✕ 祖父は忘れるっぽい → ○ 祖父は忘れっぽい. With 安い, drop the い: ✕ 安いっぽい → ○ 安っぽい.
• Thinking that any verb can take っぽい. The meaning 'does it easily' is used with only a few verbs such as 忘れる, 怒る, and 飽きる. For other verbs, use よく or 〜がち: ✕ 彼は遅れっぽい → ○ 彼はよく遅れる / 彼は遅れがちだ.

〜らしい (typical of, just like a real ...)

Noun + らしい is said about someone who really is that noun, and it is usually praise: 息子は元気で、子どもらしい (My son is lively, just as a child should be). Noun + っぽい is often said about someone who is not that noun but seems like it: 夫はときどき子どもっぽいことを言う (My husband sometimes says childish things). So 大人っぽい fits a teenager who looks older, while 大人らしい fits a real adult who acts as an adult should.

〜がち (tend to, often)

忘れっぽい describes a person's character: 祖父は忘れっぽい (My grandfather is forgetful). It works like an adjective, so it does not take an object with を. 〜がち says that something often happens, and it can take an object: 雨の日は傘を忘れがちだ (On rainy days, people tend to forget their umbrellas). ✕ 傘を忘れっぽい is not natural. がち also works with many more verbs and some nouns (遅れがち, 病気がち).

In N3 grammar-choice questions, っぽい is set against らしい, がち, and 気味. Ask two things: Is the person really that noun? Is it about character (っぽい) or about something that often happens (がち)? Also check the form before the blank: a noun or a ます-stem such as 忘れ comes right before っぽい. In sentence-ordering questions, remember that っぽい changes like an い-adjective (っぽくなる, っぽく見える). In reading, 白っぽい or 黒っぽい means 'close to that color', not exactly that color.