Reading Theme:
Invalid: Definition, Usage & Common Errors (3 meaning)
Meaning 1：not legally valid (invalid)
invalid
/ˈɪnvəlɪd/
adj.
Not legally or officially acceptable; no longer usable or in effect.
not legally valid
➕
/ˈnɒt ˈliːɡəli ˈvælɪd/
adj.
Something that is not recognized or accepted by law or official rules, often because it is out of date or lacks required elements.
📘 Details & Usage
📖 Root Explanation
From Latin 'invalidus' (in- 'not' + validus 'strong, effective'). Means 'not strong' or 'not effective'.
💡 Mnemonic
IN the VALID world, this is OUT.
📖 Example
She couldn't enter the concert because her ticket was invalid; it had expired the week before.
She couldn't enter the concert because her ticket was invalid; it had expired the week before.
🔗 Collocations
invalid passport – A passport that is no longer legally acceptable for travel.
invalid contract – A legal agreement that is not binding or enforceable.
invalid argument – A line of reasoning that is not sound or acceptable.
🔄 Synonyms
void (adj.) – Completely lacking legal force or effect.
expired (adj.) – No longer valid because a set period has ended.
null and void (adj. phrase) – A formal expression meaning completely invalid.
🚫 Antonyms
valid (adj.) – Legally or officially acceptable and in effect.
current (adj.) – Up-to-date and still applicable.
legally binding (adj. phrase) – Enforceable by law.
🌱 Derivatives
invalidity (n.) – The state of being invalid; lack of legal force.
invalidate (v.) – To make something invalid or without legal force.
📖 Cultural Story
Derived from Latin 'invalidus', it originally described someone physically weak. Its sense broadened in legal and logical contexts to mean 'lacking force, efficacy, or validity'.
Meaning 2：logically flawed (invalid)
invalid
/ˈɪnvəlɪd/
adj.
Based on incorrect information or faulty reasoning; not true or acceptable.
logically flawed
➕
/ˈlɒdʒɪkli flɔːd/
adj.
An argument, theory, or conclusion that is incorrect because it is based on wrong information, poor logic, or unsound reasoning.
📘 Details & Usage
📖 Example
His theory was proven invalid during the science class debate because he couldn't provide any solid evidence to support it.
His theory was proven invalid during the science class debate because he couldn't provide any solid evidence to support it.
🔗 Collocations
invalid assumption – A starting point for reasoning that is incorrect.
invalid conclusion – A final judgment or decision reached through faulty logic.
render invalid – To cause an idea or argument to become incorrect.
🔄 Synonyms
fallacious (adj.) – Containing a mistake in reasoning; misleading.
unsound (adj.) – Not based on reliable evidence or good judgment.
erroneous (adj.) – Incorrect; based on error.
Meaning 3：chronically ill person (invalid)
invalid
/ˈɪnvəlɪd/
adj.
(Historical/dated use) Suffering from a long-term illness or injury; very weak and unable to care for oneself.
chronically ill person
➕
/ˈkrɒnɪkli ɪl ˈpɜːsən/
adj.
A person who is weakened or disabled by a long-lasting illness or injury, often requiring care.
📘 Details & Usage
📖 Example
In the historical novel, the elderly character became an invalid after a long illness and spent most of his days in a special chair by the window.
In the historical novel, the elderly character became an invalid after a long illness and spent most of his days in a special chair by the window.
🔗 Collocations
become an invalid – To become chronically ill or disabled.
🔄 Synonyms
patient (n.) – A person receiving medical treatment (more modern and neutral).
convalescent (n.) – A person recovering from illness (implies a process of getting better).
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