n. 25B6; noun
they are planning a new extension : ADDITION, add-on, adjunct, annexe, wing, supplementary building; N. Amer. ell.
an extension of knowledge : EXPANSION, increase, enlargement, widening, broadening, deepening; augmentation, enhancement, development, growth, continuation.
an extension of opening hours : PROLONGATION, lengthening, increase.
I need an extension of time : POSTPONEMENT, deferral, delay, more/extra time.