1. now and then or here and there

    e.g. he was arrogant and occasionally callous
           open areas are only occasionally interrupted by clumps of trees
           they visit New York on occasion
           now and again she would take her favorite book from the shelf and read to us
           as we drove along, the beautiful scenery now and then attracted his attention

    Synonym: occasionallyon occasiononce in a whilenow and thenat timesfrom time to time