Poor, indigent, needy, destitute, penniless, impecunious, poverty-stricken, necessitous are comparable when they mean having less money or fewer possessions than are required to support a full life.
Poor describes a person, a people, or an institution that comes under this description; it is the most general term of the group, applying not only to those who are in actual want or to those in straitened circumstances, but also to those who, as compared to other groups, live below the level of what is regarded as comfortable.
Between indigent and needy there is very little difference in meaning, both implying urgent and pressing want; both, but especially indigent, may be used to express the state of want to which those who are poor are reduced.
Destitute goes further than any of these words in its implication of acute and dire need. It implies a lack of fundamental resources or a deprivation of basic necessities of life.
Penniless may imply a state of destitution or of indigence but it also may suggest an often temporary state of being without money; consequently, the term is susceptible of wider use than any of the others, sometimes connoting poverty or an approach to it and sometimes a mere transitory inconvenience.
Impecunious, though it carries practically the same basic suggestion as penniless, is not quite its equivalent; it may imply the deprivation of money but it more often suggests a habitual being without money and, sometimes, connotes also the habit of borrowing or of living upon one’s friends.
Poverty-stricken may be chosen as an especially vivid word suggesting the state of one who is extremely indigent or actually destitute; it often connotes the suffering caused by this condition.
Necessitous comes close to needy in meaning but often carries a clearer connotation of insistent or persistent demands for relief.