Synonym: attentive, lively, nimble, on the job, prompt, ready, watchful, dull, slow, torpid. Similar words: dealer, ruler, clerk, killer, gallery, clergy, hitler, bowler. Meaning: [ə'lɜːt] 
n. 1. condition of heightened watchfulness or preparation for action 2. a warning serves to make you more alert to danger 3. an automatic signal (usually a sound) warning of danger. v. warn or arouse to a sense of danger or call to a state of preparedness. adj. 1. very attentive or observant 2. mentally responsive 3. not unconscious; especially having become conscious 4. (usually followed by `to') showing acute awareness; mentally perceptive.
n. 1. condition of heightened watchfulness or preparation for action 2. a warning serves to make you more alert to danger 3. an automatic signal (usually a sound) warning of danger. v. warn or arouse to a sense of danger or call to a state of preparedness. adj. 1. very attentive or observant 2. mentally responsive 3. not unconscious; especially having become conscious 4. (usually followed by `to') showing acute awareness; mentally perceptive. 
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61. The district was put on red alert during a terrorist's bomb scare.
62. Police are warning the public to be on the alert for suspicious packages.
63. They rang the church bells to sound the alert and the villagers then fled.
64. The alert was called off when it was found that the bomb was not live.
65. The authorities should have been alert to the possibility of invasion.
66. He wanted to alert people to the activities of the group.
67. The rabbit seems to be very alert all its life.
68. He was as mentally alert as a man half his age.
69. The station was closed for two hours because of a security alert.
70. They want to be on the alert for similar buying opportunities.
71. Police warned the public to be on the alert for suspected terrorists.
72. Parents should be alert to sudden changes in children's behaviour.
73. The patrol police on duty are on the alert against any possible disturbances.
74. Following the bomb blast[sentencedict.com], local hospitals have been put on red alert .
75. Strategically placed video cameras can alert police to any trouble.
76. I must alert him to the need to solve the problem.
77. He waited in the darkness, his ears alert for the slightest sound.
78. The army was put on alert as the peace talks began to fail.
79. There was a noise outside and he was suddenly alert.
80. The army was yesterday placed on a state of alert in case of more riots.
81. The water authority has issued a red alert until the cause of the pollution has been removed.
82. Troops in the Philippines have been put on full alert in anticipation of trouble during a planned general strike.
83. Although he's over eighty his mind is still remarkably alert.
84. There were 15 minutes between the first air raid alert and the sounding of the all-clear signal.
85. In our reading we should always be alert for idiomatic expressions.
85. Sentencedict.com is a online sentence dictionary, on which you can find excellent sentences for a large number of words.
86. Jack was as mentally alert as a man half his age.
87. The army was on red alert against the possibility of an attack.
88. Taking notes is one of the best ways to stay alert in lectures.
89. After the security alert, most of the firms affected were open for business on Monday morning.
90. You should always be on the alert for anyone who looks suspicious.