economical adj.
VERBS be, seem Solid fuel would be more economical.
ADV. extremely, highly, remarkably, very This new oven is highly economical. | fairly, quite
PREP. in This arrangement is more economical in its use of staff. | of more economical of time and resources | with This arrangement is more economical with space.
You can also check other dicts: economical (English, 中文解释 ), wordnet sense, Collins Definition