latch on

US /lætʃ ɑːn/
UK /lætʃ ɑːn/
"latch on" picture
1.

to understand something completely

:
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It took him a while to latch on to the new concept.
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The students quickly latched on to the teacher's instructions.
:
graspcomprehendunderstandfathomapprehend
2.

to become attached to or fix oneself firmly to something

:
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The baby latched on to her mother's finger.
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The dog latched on to the bone and wouldn't let go.
:
clingadherestickfastengrip