General rules for masculine words:
- Words that end with –o. Camino (path), año (year), hijo (son/child), hermano (brother), etc.
- The majority of words that end with –s. Paréntesis (Parenthesis), análisis (analysis), país (country), mes (month), interés (interest), etc.
- The majority of words that end with –n. Almacén (store), botón (button), camión (truck), volcán (volcano), corazón (heart), etc.
- Many words that end with -l. Papel (paper), pastel (pastry), cartel (poster), hotel (hotel), cancel (cancellation), etc.
- The majority of words that originate from Greek, ending in –a, –ma, –grama. Día (day), mapa (map), problema (problem), clima (climate), sistema (system), programa (program), diagrama (diagram), dilema (dilema), panorama (panorama), telegrama (telegram), etc.
- The majority of words that end with –r. Olor (smell), comedor (dining room), motor (motor), corredor (runner), lugar (place), professor (professor), etc.