"rack one's brain" meaning in English

{
  "etymology_text": ": rack one's brain < → δείτε τις λέξεις rack, one's και brain",
  "forms": [
    {
      "form": "rack one's brain"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "phrase",
  "related": [
    {
      "word": "rack one's brains"
    }
  ],
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Ιδιωματισμοί (αγγλικά)",
          "parents": [],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "I racked my brain (trying) to remember him but it was impossible for me to.",
          "translation": "Βασάνισα το μυαλό μου να τον θυμηθώ αλλά στάθηκε αδύνατο."
        }
      ],
      "glosses": [
        "βασανίζω το μυαλό μου"
      ],
      "id": "el-rack_one's_brain-en-phrase-NUpACfc4",
      "raw_tags": [
        "ιδιωματισμός"
      ]
    }
  ],
  "word": "rack one's brain"
}

{
  "etymology_text": ": rack one's brain < → δείτε τις λέξεις rack, one's και brain",
  "forms": [
    {
      "form": "rack one's brain"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "phrase",
  "related": [
    {
      "word": "rack one's brains"
    }
  ],
  "senses": [
    {
      "categories": [
        "Ιδιωματισμοί (αγγλικά)"
      ],
      "examples": [
        {
          "text": "I racked my brain (trying) to remember him but it was impossible for me to.",
          "translation": "Βασάνισα το μυαλό μου να τον θυμηθώ αλλά στάθηκε αδύνατο."
        }
      ],
      "glosses": [
        "βασανίζω το μυαλό μου"
      ],
      "raw_tags": [
        "ιδιωματισμός"
      ]
    }
  ],
  "word": "rack one's brain"
}